Array
_.chunk
_.compact
_.concat
_.difference
_.differenceBy
_.differenceWith
_.drop
_.dropRight
_.dropRightWhile
_.dropWhile
_.fill
_.findIndex
_.findLastIndex
_.first
→ head
_.flatten
_.flattenDeep
_.flattenDepth
_.fromPairs
_.head
_.indexOf
_.initial
_.intersection
_.intersectionBy
_.intersectionWith
_.join
_.last
_.lastIndexOf
_.nth
_.pull
_.pullAll
_.pullAllBy
_.pullAllWith
_.pullAt
_.remove
_.reverse
_.slice
_.sortedIndex
_.sortedIndexBy
_.sortedIndexOf
_.sortedLastIndex
_.sortedLastIndexBy
_.sortedLastIndexOf
_.sortedUniq
_.sortedUniqBy
_.tail
_.take
_.takeRight
_.takeRightWhile
_.takeWhile
_.union
_.unionBy
_.unionWith
_.uniq
_.uniqBy
_.uniqWith
_.unzip
_.unzipWith
_.without
_.xor
_.xorBy
_.xorWith
_.zip
_.zipObject
_.zipObjectDeep
_.zipWith
Collection
_.countBy
_.each
→ forEach
_.eachRight
→ forEachRight
_.every
_.filter
_.find
_.findLast
_.flatMap
_.flatMapDeep
_.flatMapDepth
_.forEach
_.forEachRight
_.groupBy
_.includes
_.invokeMap
_.keyBy
_.map
_.orderBy
_.partition
_.reduce
_.reduceRight
_.reject
_.sample
_.sampleSize
_.shuffle
_.size
_.some
_.sortBy
Date
Function
Lang
_.castArray
_.clone
_.cloneDeep
_.cloneDeepWith
_.cloneWith
_.eq
_.gt
_.gte
_.isArguments
_.isArray
_.isArrayBuffer
_.isArrayLike
_.isArrayLikeObject
_.isBoolean
_.isBuffer
_.isDate
_.isElement
_.isEmpty
_.isEqual
_.isEqualWith
_.isError
_.isFinite
_.isFunction
_.isInteger
_.isLength
_.isMap
_.isMatch
_.isMatchWith
_.isNaN
_.isNative
_.isNil
_.isNull
_.isNumber
_.isObject
_.isObjectLike
_.isPlainObject
_.isRegExp
_.isSafeInteger
_.isSet
_.isString
_.isSymbol
_.isTypedArray
_.isUndefined
_.isWeakMap
_.isWeakSet
_.lt
_.lte
_.toArray
_.toInteger
_.toLength
_.toNumber
_.toPlainObject
_.toSafeInteger
_.toString
Math
Object
_.assign
_.assignIn
_.assignInWith
_.assignWith
_.at
_.create
_.defaults
_.defaultsDeep
_.entries
→ toPairs
_.entriesIn
→ toPairsIn
_.extend
→ assignIn
_.extendWith
→ assignInWith
_.findKey
_.findLastKey
_.forIn
_.forInRight
_.forOwn
_.forOwnRight
_.functions
_.functionsIn
_.get
_.has
_.hasIn
_.invert
_.invertBy
_.invoke
_.keys
_.keysIn
_.mapKeys
_.mapValues
_.merge
_.mergeWith
_.omit
_.omitBy
_.pick
_.pickBy
_.result
_.set
_.setWith
_.toPairs
_.toPairsIn
_.transform
_.unset
_.update
_.updateWith
_.values
_.valuesIn
Seq
String
_.camelCase
_.capitalize
_.deburr
_.endsWith
_.escape
_.escapeRegExp
_.kebabCase
_.lowerCase
_.lowerFirst
_.pad
_.padEnd
_.padStart
_.parseInt
_.repeat
_.replace
_.snakeCase
_.split
_.startCase
_.startsWith
_.template
_.toLower
_.toUpper
_.trim
_.trimEnd
_.trimStart
_.truncate
_.unescape
_.upperCase
_.upperFirst
_.words
Util
Properties
Methods
“Array” Methods
_.chunk(array, [size=1])
Creates an array of elements split into groups the length of size
.
If array
can’t be split evenly, the final chunk will be the remaining
elements.
3.0.0
array
(Array): The array to process.[size=1]
(number): The length of each chunk(Array): Returns the new array containing chunks.
_.chunk(['a', 'b', 'c', 'd'], 2);
// → [['a', 'b'], ['c', 'd']]
_.chunk(['a', 'b', 'c', 'd'], 3);
// → [['a', 'b', 'c'], ['d']]
_.compact(array)
Creates an array with all falsey values removed. The values false
, null
,
0
, ""
, undefined
, and NaN
are falsey.
0.1.0
array
(Array): The array to compact.(Array): Returns the new array of filtered values.
_.compact([0, 1, false, 2, '', 3]);
// → [1, 2, 3]
_.concat(array, [values])
Creates a new array concatenating array
with any additional arrays
and/or values.
4.0.0
array
(Array): The array to concatenate.[values]
(…*): The values to concatenate.(Array): Returns the new concatenated array.
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);
console.log(other);
// → [1, 2, 3, [4]]
console.log(array);
// → [1]
_.difference(array, [values])
Creates an array of unique array
values not included in the other given
arrays using SameValueZero
for equality comparisons. The order of result values is determined by the
order they occur in the first array.
0.1.0
array
(Array): The array to inspect.[values]
(…Array): The values to exclude.(Array): Returns the new array of filtered values.
_.difference([3, 2, 1], [4, 2]);
// → [3, 1]
_.differenceBy(array, [values], [iteratee=_.identity])
This method is like _.difference
except that it accepts iteratee
which
is invoked for each element of array
and values
to generate the criterion
by which they're compared. Result values are chosen from the first array.
The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The array to inspect.[values]
(…Array): The values to exclude.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Array): Returns the new array of filtered values.
_.differenceBy([3.1, 2.2, 1.3], [4.4, 2.5], Math.floor);
// → [3.1, 1.3]
// The `_.property` iteratee shorthand.
_.differenceBy([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], 'x');
// → [{ 'x': 2 }]
_.differenceWith(array, [values], [comparator])
This method is like _.difference
except that it accepts comparator
which is invoked to compare elements of array
to values
. Result values
are chosen from the first array. The comparator is invoked with two arguments:
(arrVal, othVal).
4.0.0
array
(Array): The array to inspect.[values]
(…Array): The values to exclude.[comparator]
(Function): The comparator invoked per element.(Array): Returns the new array of filtered values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// → [{ 'x': 2, 'y': 1 }]
_.drop(array, [n=1])
Creates a slice of array
with n
elements dropped from the beginning.
0.5.0
array
(Array): The array to query.[n=1]
(number): The number of elements to drop.(Array): Returns the slice of array
.
_.drop([1, 2, 3]);
// → [2, 3]
_.drop([1, 2, 3], 2);
// → [3]
_.drop([1, 2, 3], 5);
// → []
_.drop([1, 2, 3], 0);
// → [1, 2, 3]
_.dropRight(array, [n=1])
Creates a slice of array
with n
elements dropped from the end.
3.0.0
array
(Array): The array to query.[n=1]
(number): The number of elements to drop.(Array): Returns the slice of array
.
_.dropRight([1, 2, 3]);
// → [1, 2]
_.dropRight([1, 2, 3], 2);
// → [1]
_.dropRight([1, 2, 3], 5);
// → []
_.dropRight([1, 2, 3], 0);
// → [1, 2, 3]
_.dropRightWhile(array, [predicate=_.identity])
Creates a slice of array
excluding elements dropped from the end.
Elements are dropped until predicate
returns falsey. The predicate is
invoked with three arguments: (value, index, array).
3.0.0
array
(Array): The array to query.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.dropRightWhile(users, function(o) { return !o.active; });
// → objects for ['barney']
// The `_.matches` iteratee shorthand.
_.dropRightWhile(users, { 'user': 'pebbles', 'active': false });
// → objects for ['barney', 'fred']
// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(users, ['active', false]);
// → objects for ['barney']
// The `_.property` iteratee shorthand.
_.dropRightWhile(users, 'active');
// → objects for ['barney', 'fred', 'pebbles']
_.dropWhile(array, [predicate=_.identity])
Creates a slice of array
excluding elements dropped from the beginning.
Elements are dropped until predicate
returns falsey. The predicate is
invoked with three arguments: (value, index, array).
3.0.0
array
(Array): The array to query.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.dropWhile(users, function(o) { return !o.active; });
// → objects for ['pebbles']
// The `_.matches` iteratee shorthand.
_.dropWhile(users, { 'user': 'barney', 'active': false });
// → objects for ['fred', 'pebbles']
// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(users, ['active', false]);
// → objects for ['pebbles']
// The `_.property` iteratee shorthand.
_.dropWhile(users, 'active');
// → objects for ['barney', 'fred', 'pebbles']
_.fill(array, value, [start=0], [end=array.length])
Fills elements of array
with value
from start
up to, but not
including, end
.
Note: This method mutates array
.
3.2.0
array
(Array): The array to fill.value
(*): The value to fill array
with.[start=0]
(number): The start position.[end=array.length]
(number): The end position.(Array): Returns array
.
var array = [1, 2, 3];
_.fill(array, 'a');
console.log(array);
// → ['a', 'a', 'a']
_.fill(Array(3), 2);
// → [2, 2, 2]
_.fill([4, 6, 8, 10], '*', 1, 3);
// → [4, '*', '*', 10]
_.findIndex(array, [predicate=_.identity])
This method is like _.find
except that it returns the index of the first
element predicate
returns truthy for instead of the element itself.
1.1.0
array
(Array): The array to search.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(number): Returns the index of the found element, else -1
.
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.findIndex(users, function(o) { return o.user == 'barney'; });
// → 0
// The `_.matches` iteratee shorthand.
_.findIndex(users, { 'user': 'fred', 'active': false });
// → 1
// The `_.matchesProperty` iteratee shorthand.
_.findIndex(users, ['active', false]);
// → 0
// The `_.property` iteratee shorthand.
_.findIndex(users, 'active');
// → 2
_.findLastIndex(array, [predicate=_.identity])
This method is like _.findIndex
except that it iterates over elements
of collection
from right to left.
2.0.0
array
(Array): The array to search.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(number): Returns the index of the found element, else -1
.
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.findLastIndex(users, function(o) { return o.user == 'pebbles'; });
// → 2
// The `_.matches` iteratee shorthand.
_.findLastIndex(users, { 'user': 'barney', 'active': true });
// → 0
// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(users, ['active', false]);
// → 2
// The `_.property` iteratee shorthand.
_.findLastIndex(users, 'active');
// → 0
_.flatten(array)
Flattens array
a single level deep.
0.1.0
array
(Array): The array to flatten.(Array): Returns the new flattened array.
_.flatten([1, [2, [3, [4]], 5]]);
// → [1, 2, [3, [4]], 5]
_.flattenDeep(array)
Recursively flattens array
.
3.0.0
array
(Array): The array to flatten.(Array): Returns the new flattened array.
_.flattenDeep([1, [2, [3, [4]], 5]]);
// → [1, 2, 3, 4, 5]
_.flattenDepth(array, [depth=1])
Recursively flatten array
up to depth
times.
4.4.0
array
(Array): The array to flatten.[depth=1]
(number): The maximum recursion depth.(Array): Returns the new flattened array.
var array = [1, [2, [3, [4]], 5]];
_.flattenDepth(array, 1);
// → [1, 2, [3, [4]], 5]
_.flattenDepth(array, 2);
// → [1, 2, 3, [4], 5]
_.fromPairs(pairs)
The inverse of _.toPairs
; this method returns an object composed
from key-value pairs
.
4.0.0
pairs
(Array): The key-value pairs.(Object): Returns the new object.
_.fromPairs([['fred', 30], ['barney', 40]]);
// → { 'fred': 30, 'barney': 40 }
_.head(array)
Gets the first element of array
.
0.1.0
_.first
array
(Array): The array to query.(*): Returns the first element of array
.
_.head([1, 2, 3]);
// → 1
_.head([]);
// → undefined
_.indexOf(array, value, [fromIndex=0])
Gets the index at which the first occurrence of value
is found in array
using SameValueZero
for equality comparisons. If fromIndex
is negative, it’s used as the
offset from the end of array
.
0.1.0
array
(Array): The array to search.value
(*): The value to search for.[fromIndex=0]
(number): The index to search from.(number): Returns the index of the matched value, else -1
.
_.indexOf([1, 2, 1, 2], 2);
// → 1
// Search from the `fromIndex`.
_.indexOf([1, 2, 1, 2], 2, 2);
// → 3
_.initial(array)
Gets all but the last element of array
.
0.1.0
array
(Array): The array to query.(Array): Returns the slice of array
.
_.initial([1, 2, 3]);
// → [1, 2]
_.intersection([arrays])
Creates an array of unique values that are included in all given arrays
using SameValueZero
for equality comparisons. The order of result values is determined by the
order they occur in the first array.
0.1.0
[arrays]
(…Array): The arrays to inspect.(Array): Returns the new array of intersecting values.
_.intersection([2, 1], [4, 2], [1, 2]);
// → [2]
_.intersectionBy([arrays], [iteratee=_.identity])
This method is like _.intersection
except that it accepts iteratee
which is invoked for each element of each arrays
to generate the criterion
by which they're compared. Result values are chosen from the first array.
The iteratee is invoked with one argument: (value).
4.0.0
[arrays]
(…Array): The arrays to inspect.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Array): Returns the new array of intersecting values.
_.intersectionBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// → [2.1]
// The `_.property` iteratee shorthand.
_.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 1 }]
_.intersectionWith([arrays], [comparator])
This method is like _.intersection
except that it accepts comparator
which is invoked to compare elements of arrays
. Result values are chosen
from the first array. The comparator is invoked with two arguments:
(arrVal, othVal).
4.0.0
[arrays]
(…Array): The arrays to inspect.[comparator]
(Function): The comparator invoked per element.(Array): Returns the new array of intersecting values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.intersectionWith(objects, others, _.isEqual);
// → [{ 'x': 1, 'y': 2 }]
_.join(array, [separator=','])
Converts all elements in array
into a string separated by separator
.
4.0.0
array
(Array): The array to convert.[separator=',']
(string): The element separator.(string): Returns the joined string.
_.join(['a', 'b', 'c'], '~');
// → 'a~b~c'
_.last(array)
Gets the last element of array
.
0.1.0
array
(Array): The array to query.(*): Returns the last element of array
.
_.last([1, 2, 3]);
// → 3
_.lastIndexOf(array, value, [fromIndex=array.length-1])
This method is like _.indexOf
except that it iterates over elements of
array
from right to left.
0.1.0
array
(Array): The array to search.value
(*): The value to search for.[fromIndex=array.length-1]
(number): The index to search from.(number): Returns the index of the matched value, else -1
.
_.lastIndexOf([1, 2, 1, 2], 2);
// → 3
// Search from the `fromIndex`.
_.lastIndexOf([1, 2, 1, 2], 2, 2);
// → 1
_.nth(array, [n=0])
Gets the nth element of array
. If n
is negative, the nth element
from the end is returned.
4.11.0
array
(Array): The array to query.[n=0]
(number): The index of the element to return.(*): Returns the nth element of array
.
var array = ['a', 'b', 'c', 'd'];
_.nth(array, 1);
// → 'b'
_.nth(array, -2);
// → 'c';
_.pull(array, [values])
Removes all given values from array
using
SameValueZero
for equality comparisons.
Note: Unlike _.without
, this method mutates array
. Use _.remove
to remove elements from an array by predicate.
2.0.0
array
(Array): The array to modify.[values]
(…*): The values to remove.(Array): Returns array
.
var array = [1, 2, 3, 1, 2, 3];
_.pull(array, 2, 3);
console.log(array);
// → [1, 1]
_.pullAll(array, values)
This method is like _.pull
except that it accepts an array of values to remove.
Note: Unlike _.difference
, this method mutates array
.
4.0.0
array
(Array): The array to modify.values
(Array): The values to remove.(Array): Returns array
.
var array = [1, 2, 3, 1, 2, 3];
_.pullAll(array, [2, 3]);
console.log(array);
// → [1, 1]
_.pullAllBy(array, values, [iteratee=_.identity])
This method is like _.pullAll
except that it accepts iteratee
which is
invoked for each element of array
and values
to generate the criterion
by which they're compared. The iteratee is invoked with one argument: (value).
Note: Unlike _.differenceBy
, this method mutates array
.
4.0.0
array
(Array): The array to modify.values
(Array): The values to remove.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Array): Returns array
.
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];
_.pullAllBy(array, [{ 'x': 1 }, { 'x': 3 }], 'x');
console.log(array);
// → [{ 'x': 2 }]
_.pullAllWith(array, values, [comparator])
This method is like _.pullAll
except that it accepts comparator
which
is invoked to compare elements of array
to values
. The comparator is
invoked with two arguments: (arrVal, othVal).
Note: Unlike _.differenceWith
, this method mutates array
.
4.6.0
array
(Array): The array to modify.values
(Array): The values to remove.[comparator]
(Function): The comparator invoked per element.(Array): Returns array
.
var array = [{ 'x': 1, 'y': 2 }, { 'x': 3, 'y': 4 }, { 'x': 5, 'y': 6 }];
_.pullAllWith(array, [{ 'x': 3, 'y': 4 }], _.isEqual);
console.log(array);
// → [{ 'x': 1, 'y': 2 }, { 'x': 5, 'y': 6 }]
_.pullAt(array, [indexes])
Removes elements from array
corresponding to indexes
and returns an
array of removed elements.
Note: Unlike _.at
, this method mutates array
.
3.0.0
array
(Array): The array to modify.[indexes]
(…(number|number[])): The indexes of elements to remove.(Array): Returns the new array of removed elements.
var array = [5, 10, 15, 20];
var evens = _.pullAt(array, 1, 3);
console.log(array);
// → [5, 15]
console.log(evens);
// → [10, 20]
_.remove(array, [predicate=_.identity])
Removes all elements from array
that predicate
returns truthy for
and returns an array of the removed elements. The predicate is invoked
with three arguments: (value, index, array).
Note: Unlike _.filter
, this method mutates array
. Use _.pull
to pull elements from an array by value.
2.0.0
array
(Array): The array to modify.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the new array of removed elements.
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
return n % 2 == 0;
});
console.log(array);
// → [1, 3]
console.log(evens);
// → [2, 4]
_.reverse(array)
Reverses array
so that the first element becomes the last, the second
element becomes the second to last, and so on.
Note: This method mutates array
and is based on
Array#reverse
.
4.0.0
array
(Array): The array to modify.(Array): Returns array
.
var array = [1, 2, 3];
_.reverse(array);
// → [3, 2, 1]
console.log(array);
// → [3, 2, 1]
_.slice(array, [start=0], [end=array.length])
Creates a slice of array
from start
up to, but not including, end
.
Note: This method is used instead of
Array#slice
to ensure dense arrays are
returned.
3.0.0
array
(Array): The array to slice.[start=0]
(number): The start position.[end=array.length]
(number): The end position.(Array): Returns the slice of array
.
_.sortedIndex(array, value)
Uses a binary search to determine the lowest index at which value
should be inserted into array
in order to maintain its sort order.
0.1.0
array
(Array): The sorted array to inspect.value
(*): The value to evaluate.(number): Returns the index at which value
should be inserted into array
.
_.sortedIndex([30, 50], 40);
// → 1
_.sortedIndex([4, 5], 4);
// → 0
_.sortedIndexBy(array, value, [iteratee=_.identity])
This method is like _.sortedIndex
except that it accepts iteratee
which is invoked for value
and each element of array
to compute their
sort ranking. The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The sorted array to inspect.value
(*): The value to evaluate.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(number): Returns the index at which value
should be inserted into array
.
var dict = { 'thirty': 30, 'forty': 40, 'fifty': 50 };
_.sortedIndexBy(['thirty', 'fifty'], 'forty', _.propertyOf(dict));
// → 1
// The `_.property` iteratee shorthand.
_.sortedIndexBy([{ 'x': 4 }, { 'x': 5 }], { 'x': 4 }, 'x');
// → 0
_.sortedIndexOf(array, value)
This method is like _.indexOf
except that it performs a binary
search on a sorted array
.
4.0.0
array
(Array): The array to search.value
(*): The value to search for.(number): Returns the index of the matched value, else -1
.
_.sortedIndexOf([1, 1, 2, 2], 2);
// → 2
_.sortedLastIndex(array, value)
This method is like _.sortedIndex
except that it returns the highest
index at which value
should be inserted into array
in order to
maintain its sort order.
3.0.0
array
(Array): The sorted array to inspect.value
(*): The value to evaluate.(number): Returns the index at which value
should be inserted into array
.
_.sortedLastIndex([4, 5], 4);
// → 1
_.sortedLastIndexBy(array, value, [iteratee=_.identity])
This method is like _.sortedLastIndex
except that it accepts iteratee
which is invoked for value
and each element of array
to compute their
sort ranking. The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The sorted array to inspect.value
(*): The value to evaluate.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(number): Returns the index at which value
should be inserted into array
.
// The `_.property` iteratee shorthand.
_.sortedLastIndexBy([{ 'x': 4 }, { 'x': 5 }], { 'x': 4 }, 'x');
// → 1
_.sortedLastIndexOf(array, value)
This method is like _.lastIndexOf
except that it performs a binary
search on a sorted array
.
4.0.0
array
(Array): The array to search.value
(*): The value to search for.(number): Returns the index of the matched value, else -1
.
_.sortedLastIndexOf([1, 1, 2, 2], 2);
// → 3
_.sortedUniq(array)
This method is like _.uniq
except that it’s designed and optimized
for sorted arrays.
4.0.0
array
(Array): The array to inspect.(Array): Returns the new duplicate free array.
_.sortedUniq([1, 1, 2]);
// → [1, 2]
_.sortedUniqBy(array, [iteratee])
This method is like _.uniqBy
except that it’s designed and optimized
for sorted arrays.
4.0.0
array
(Array): The array to inspect.[iteratee]
(Function): The iteratee invoked per element.(Array): Returns the new duplicate free array.
_.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
// → [1.1, 2.3]
_.tail(array)
Gets all but the first element of array
.
4.0.0
array
(Array): The array to query.(Array): Returns the slice of array
.
_.tail([1, 2, 3]);
// → [2, 3]
_.take(array, [n=1])
Creates a slice of array
with n
elements taken from the beginning.
0.1.0
array
(Array): The array to query.[n=1]
(number): The number of elements to take.(Array): Returns the slice of array
.
_.take([1, 2, 3]);
// → [1]
_.take([1, 2, 3], 2);
// → [1, 2]
_.take([1, 2, 3], 5);
// → [1, 2, 3]
_.take([1, 2, 3], 0);
// → []
_.takeRight(array, [n=1])
Creates a slice of array
with n
elements taken from the end.
3.0.0
array
(Array): The array to query.[n=1]
(number): The number of elements to take.(Array): Returns the slice of array
.
_.takeRight([1, 2, 3]);
// → [3]
_.takeRight([1, 2, 3], 2);
// → [2, 3]
_.takeRight([1, 2, 3], 5);
// → [1, 2, 3]
_.takeRight([1, 2, 3], 0);
// → []
_.takeRightWhile(array, [predicate=_.identity])
Creates a slice of array
with elements taken from the end. Elements are
taken until predicate
returns falsey. The predicate is invoked with
three arguments: (value, index, array).
3.0.0
array
(Array): The array to query.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.takeRightWhile(users, function(o) { return !o.active; });
// → objects for ['fred', 'pebbles']
// The `_.matches` iteratee shorthand.
_.takeRightWhile(users, { 'user': 'pebbles', 'active': false });
// → objects for ['pebbles']
// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(users, ['active', false]);
// → objects for ['fred', 'pebbles']
// The `_.property` iteratee shorthand.
_.takeRightWhile(users, 'active');
// → []
_.takeWhile(array, [predicate=_.identity])
Creates a slice of array
with elements taken from the beginning. Elements
are taken until predicate
returns falsey. The predicate is invoked with
three arguments: (value, index, array).
3.0.0
array
(Array): The array to query.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false},
{ 'user': 'pebbles', 'active': true }
];
_.takeWhile(users, function(o) { return !o.active; });
// → objects for ['barney', 'fred']
// The `_.matches` iteratee shorthand.
_.takeWhile(users, { 'user': 'barney', 'active': false });
// → objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(users, ['active', false]);
// → objects for ['barney', 'fred']
// The `_.property` iteratee shorthand.
_.takeWhile(users, 'active');
// → []
_.union([arrays])
Creates an array of unique values, in order, from all given arrays using
SameValueZero
for equality comparisons.
0.1.0
[arrays]
(…Array): The arrays to inspect.(Array): Returns the new array of combined values.
_.union([2, 1], [4, 2], [1, 2]);
// → [2, 1, 4]
_.unionBy([arrays], [iteratee=_.identity])
This method is like _.union
except that it accepts iteratee
which is
invoked for each element of each arrays
to generate the criterion by
which uniqueness is computed. The iteratee is invoked with one argument:
(value).
4.0.0
[arrays]
(…Array): The arrays to inspect.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Array): Returns the new array of combined values.
_.unionBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// → [2.1, 1.2, 4.3]
// The `_.property` iteratee shorthand.
_.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 1 }, { 'x': 2 }]
_.unionWith([arrays], [comparator])
This method is like _.union
except that it accepts comparator
which
is invoked to compare elements of arrays
. The comparator is invoked
with two arguments: (arrVal, othVal).
4.0.0
[arrays]
(…Array): The arrays to inspect.[comparator]
(Function): The comparator invoked per element.(Array): Returns the new array of combined values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.unionWith(objects, others, _.isEqual);
// → [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
_.uniq(array)
Creates a duplicate-free version of an array, using
SameValueZero
for equality comparisons, in which only the first occurrence of each
element is kept.
0.1.0
array
(Array): The array to inspect.(Array): Returns the new duplicate free array.
_.uniq([2, 1, 2]);
// → [2, 1]
_.uniqBy(array, [iteratee=_.identity])
This method is like _.uniq
except that it accepts iteratee
which is
invoked for each element in array
to generate the criterion by which
uniqueness is computed. The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The array to inspect.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Array): Returns the new duplicate free array.
_.uniqBy([2.1, 1.2, 2.3], Math.floor);
// → [2.1, 1.2]
// The `_.property` iteratee shorthand.
_.uniqBy([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 1 }, { 'x': 2 }]
_.uniqWith(array, [comparator])
This method is like _.uniq
except that it accepts comparator
which
is invoked to compare elements of array
. The comparator is invoked with
two arguments: (arrVal, othVal).
4.0.0
array
(Array): The array to inspect.[comparator]
(Function): The comparator invoked per element.(Array): Returns the new duplicate free array.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.uniqWith(objects, _.isEqual);
// → [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]
_.unzip(array)
This method is like _.zip
except that it accepts an array of grouped
elements and creates an array regrouping the elements to their pre-zip
configuration.
1.2.0
array
(Array): The array of grouped elements to process.(Array): Returns the new array of regrouped elements.
var zipped = _.zip(['fred', 'barney'], [30, 40], [true, false]);
// → [['fred', 30, true], ['barney', 40, false]]
_.unzip(zipped);
// → [['fred', 'barney'], [30, 40], [true, false]]
_.unzipWith(array, [iteratee=_.identity])
This method is like _.unzip
except that it accepts iteratee
to specify
how regrouped values should be combined. The iteratee is invoked with the
elements of each group: (…group).
3.8.0
array
(Array): The array of grouped elements to process.[iteratee=_.identity]
(Function): The function to combine regrouped values.(Array): Returns the new array of regrouped elements.
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// → [[1, 10, 100], [2, 20, 200]]
_.unzipWith(zipped, _.add);
// → [3, 30, 300]
_.without(array, [values])
Creates an array excluding all given values using
SameValueZero
for equality comparisons.
0.1.0
array
(Array): The array to filter.[values]
(…*): The values to exclude.(Array): Returns the new array of filtered values.
_.without([1, 2, 1, 3], 1, 2);
// → [3]
_.xor([arrays])
Creates an array of unique values that is the symmetric difference of the given arrays. The order of result values is determined by the order they occur in the arrays.
2.4.0
[arrays]
(…Array): The arrays to inspect.(Array): Returns the new array of values.
_.xor([2, 1], [4, 2]);
// → [1, 4]
_.xorBy([arrays], [iteratee=_.identity])
This method is like _.xor
except that it accepts iteratee
which is
invoked for each element of each arrays
to generate the criterion by
which by which they're compared. The iteratee is invoked with one argument:
(value).
4.0.0
[arrays]
(…Array): The arrays to inspect.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Array): Returns the new array of values.
_.xorBy([2.1, 1.2], [4.3, 2.4], Math.floor);
// → [1.2, 4.3]
// The `_.property` iteratee shorthand.
_.xorBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
// → [{ 'x': 2 }]
_.xorWith([arrays], [comparator])
This method is like _.xor
except that it accepts comparator
which is
invoked to compare elements of arrays
. The comparator is invoked with
two arguments: (arrVal, othVal).
4.0.0
[arrays]
(…Array): The arrays to inspect.[comparator]
(Function): The comparator invoked per element.(Array): Returns the new array of values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.xorWith(objects, others, _.isEqual);
// → [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
_.zip([arrays])
Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
0.1.0
[arrays]
(…Array): The arrays to process.(Array): Returns the new array of grouped elements.
_.zip(['fred', 'barney'], [30, 40], [true, false]);
// → [['fred', 30, true], ['barney', 40, false]]
_.zipObject([props=[]], [values=[]])
This method is like _.fromPairs
except that it accepts two arrays,
one of property identifiers and one of corresponding values.
0.4.0
[props=[]]
(Array): The property identifiers.[values=[]]
(Array): The property values.(Object): Returns the new object.
_.zipObject(['a', 'b'], [1, 2]);
// → { 'a': 1, 'b': 2 }
_.zipObjectDeep([props=[]], [values=[]])
This method is like _.zipObject
except that it supports property paths.
4.1.0
[props=[]]
(Array): The property identifiers.[values=[]]
(Array): The property values.(Object): Returns the new object.
_.zipObjectDeep(['a.b[0].c', 'a.b[1].d'], [1, 2]);
// → { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }
_.zipWith([arrays], [iteratee=_.identity])
This method is like _.zip
except that it accepts iteratee
to specify
how grouped values should be combined. The iteratee is invoked with the
elements of each group: (…group).
3.8.0
[arrays]
(…Array): The arrays to process.[iteratee=_.identity]
(Function): The function to combine grouped values.(Array): Returns the new array of grouped elements.
_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
return a + b + c;
});
// → [111, 222]
“Collection” Methods
_.countBy(collection, [iteratee=_.identity])
Creates an object composed of keys generated from the results of running
each element of collection
thru iteratee
. The corresponding value of
each key is the number of times the key was returned by iteratee
. The
iteratee is invoked with one argument: (value).
0.5.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee to transform keys.(Object): Returns the composed aggregate object.
_.countBy([6.1, 4.2, 6.3], Math.floor);
// → { '4': 1, '6': 2 }
_.countBy(['one', 'two', 'three'], 'length');
// → { '3': 2, '5': 1 }
_.every(collection, [predicate=_.identity])
Checks if predicate
returns truthy for all elements of collection
.
Iteration is stopped once predicate
returns falsey. The predicate is
invoked with three arguments: (value, index|key, collection).
0.1.0
collection
(Array|Object): The collection to iterate over.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(boolean): Returns true
if all elements pass the predicate check, else false
.
_.every([true, 1, null, 'yes'], Boolean);
// → false
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': false }
];
// The `_.matches` iteratee shorthand.
_.every(users, { 'user': 'barney', 'active': false });
// → false
// The `_.matchesProperty` iteratee shorthand.
_.every(users, ['active', false]);
// → true
// The `_.property` iteratee shorthand.
_.every(users, 'active');
// → false
_.filter(collection, [predicate=_.identity])
Iterates over elements of collection
, returning an array of all elements
predicate
returns truthy for. The predicate is invoked with three
arguments: (value, index|key, collection).
0.1.0
collection
(Array|Object): The collection to iterate over.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the new filtered array.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
_.filter(users, function(o) { return !o.active; });
// → objects for ['fred']
// The `_.matches` iteratee shorthand.
_.filter(users, { 'age': 36, 'active': true });
// → objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.filter(users, ['active', false]);
// → objects for ['fred']
// The `_.property` iteratee shorthand.
_.filter(users, 'active');
// → objects for ['barney']
_.find(collection, [predicate=_.identity])
Iterates over elements of collection
, returning the first element
predicate
returns truthy for. The predicate is invoked with three
arguments: (value, index|key, collection).
0.1.0
collection
(Array|Object): The collection to search.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(*): Returns the matched element, else undefined
.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
];
_.find(users, function(o) { return o.age < 40; });
// → object for 'barney'
// The `_.matches` iteratee shorthand.
_.find(users, { 'age': 1, 'active': true });
// → object for 'pebbles'
// The `_.matchesProperty` iteratee shorthand.
_.find(users, ['active', false]);
// → object for 'fred'
// The `_.property` iteratee shorthand.
_.find(users, 'active');
// → object for 'barney'
_.findLast(collection, [predicate=_.identity])
This method is like _.find
except that it iterates over elements of
collection
from right to left.
2.0.0
collection
(Array|Object): The collection to search.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(*): Returns the matched element, else undefined
.
_.findLast([1, 2, 3, 4], function(n) {
return n % 2 == 1;
});
// → 3
_.flatMap(collection, [iteratee=_.identity])
Creates a flattened array of values by running each element in collection
thru iteratee
and flattening the mapped results. The iteratee is invoked
with three arguments: (value, index|key, collection).
4.0.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the new flattened array.
function duplicate(n) {
return [n, n];
}
_.flatMap([1, 2], duplicate);
// → [1, 1, 2, 2]
_.flatMapDeep(collection, [iteratee=_.identity])
This method is like _.flatMap
except that it recursively flattens the
mapped results.
4.7.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the new flattened array.
function duplicate(n) {
return [[[n, n]]];
}
_.flatMapDeep([1, 2], duplicate);
// → [1, 1, 2, 2]
_.flatMapDepth(collection, [iteratee=_.identity], [depth=1])
This method is like _.flatMap
except that it recursively flattens the
mapped results up to depth
times.
4.7.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The function invoked per iteration.[depth=1]
(number): The maximum recursion depth.(Array): Returns the new flattened array.
function duplicate(n) {
return [[[n, n]]];
}
_.flatMapDepth([1, 2], duplicate, 2);
// → [[1, 1], [2, 2]]
_.forEach(collection, [iteratee=_.identity])
Iterates over elements of collection
and invokes iteratee
for each element.
The iteratee is invoked with three arguments: (value, index|key, collection).
Iteratee functions may exit iteration early by explicitly returning false
.
Note: As with other "Collections" methods, objects with a "length"
property are iterated like arrays. To avoid this behavior use _.forIn
or _.forOwn
for object iteration.
0.1.0
_.each
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.(*): Returns collection
.
_([1, 2]).forEach(function(value) {
console.log(value);
});
// → Logs `1` then `2`.
_.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
console.log(key);
});
// → Logs 'a' then 'b' (iteration order is not guaranteed).
_.forEachRight(collection, [iteratee=_.identity])
This method is like _.forEach
except that it iterates over elements of
collection
from right to left.
2.0.0
_.eachRight
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.(*): Returns collection
.
_.forEachRight([1, 2], function(value) {
console.log(value);
});
// → Logs `2` then `1`.
_.groupBy(collection, [iteratee=_.identity])
Creates an object composed of keys generated from the results of running
each element of collection
thru iteratee
. The order of grouped values
is determined by the order they occur in collection
. The corresponding
value of each key is an array of elements responsible for generating the
key. The iteratee is invoked with one argument: (value).
0.1.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee to transform keys.(Object): Returns the composed aggregate object.
_.groupBy([6.1, 4.2, 6.3], Math.floor);
// → { '4': [4.2], '6': [6.1, 6.3] }
// The `_.property` iteratee shorthand.
_.groupBy(['one', 'two', 'three'], 'length');
// → { '3': ['one', 'two'], '5': ['three'] }
_.includes(collection, value, [fromIndex=0])
Checks if value
is in collection
. If collection
is a string, it’s
checked for a substring of value
, otherwise
SameValueZero
is used for equality comparisons. If fromIndex
is negative, it’s used as
the offset from the end of collection
.
0.1.0
collection
(Array|Object|string): The collection to search.value
(*): The value to search for.[fromIndex=0]
(number): The index to search from.(boolean): Returns true
if value
is found, else false
.
_.includes([1, 2, 3], 1);
// → true
_.includes([1, 2, 3], 1, 2);
// → false
_.includes({ 'user': 'fred', 'age': 40 }, 'fred');
// → true
_.includes('pebbles', 'eb');
// → true
_.invokeMap(collection, path, [args])
Invokes the method at path
of each element in collection
, returning
an array of the results of each invoked method. Any additional arguments
are provided to each invoked method. If methodName
is a function, it’s
invoked for and this
bound to, each element in collection
.
4.0.0
collection
(Array|Object): The collection to iterate over.path
(Array|Function|string): The path of the method to invoke or the function invoked per iteration.[args]
(…*): The arguments to invoke each method with.(Array): Returns the array of results.
_.invokeMap([[5, 1, 7], [3, 2, 1]], 'sort');
// → [[1, 5, 7], [1, 2, 3]]
_.invokeMap([123, 456], String.prototype.split, '');
// → [['1', '2', '3'], ['4', '5', '6']]
_.keyBy(collection, [iteratee=_.identity])
Creates an object composed of keys generated from the results of running
each element of collection
thru iteratee
. The corresponding value of
each key is the last element responsible for generating the key. The
iteratee is invoked with one argument: (value).
4.0.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee to transform keys.(Object): Returns the composed aggregate object.
var array = [
{ 'dir': 'left', 'code': 97 },
{ 'dir': 'right', 'code': 100 }
];
_.keyBy(array, function(o) {
return String.fromCharCode(o.code);
});
// → { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
_.keyBy(array, 'dir');
// → { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
_.map(collection, [iteratee=_.identity])
Creates an array of values by running each element in collection
thru
iteratee
. The iteratee is invoked with three arguments:
(value, index|key, collection).
Many lodash methods are guarded to work as iteratees for methods like
_.every
, _.filter
, _.map
, _.mapValues
, _.reject
, and _.some
.
The guarded methods are:
ary
, chunk
, curry
, curryRight
, drop
, dropRight
, every
,
fill
, invert
, parseInt
, random
, range
, rangeRight
, repeat
,
sampleSize
, slice
, some
, sortBy
, split
, take
, takeRight
,
template
, trim
, trimEnd
, trimStart
, and words
0.1.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the new mapped array.
function square(n) {
return n * n;
}
_.map([4, 8], square);
// → [16, 64]
_.map({ 'a': 4, 'b': 8 }, square);
// → [16, 64] (iteration order is not guaranteed)
var users = [
{ 'user': 'barney' },
{ 'user': 'fred' }
];
// The `_.property` iteratee shorthand.
_.map(users, 'user');
// → ['barney', 'fred']
_.orderBy(collection, [iteratees=[_.identity]], [orders])
This method is like _.sortBy
except that it allows specifying the sort
orders of the iteratees to sort by. If orders
is unspecified, all values
are sorted in ascending order. Otherwise, specify an order of "desc" for
descending or "asc" for ascending sort order of corresponding values.
4.0.0
collection
(Array|Object): The collection to iterate over.[iteratees=[_.identity]]
(Array[]|Function[]|Object[]|string[]): The iteratees to sort by.[orders]
(string[]): The sort orders of iteratees
.(Array): Returns the new sorted array.
var users = [
{ 'user': 'fred', 'age': 48 },
{ 'user': 'barney', 'age': 34 },
{ 'user': 'fred', 'age': 40 },
{ 'user': 'barney', 'age': 36 }
];
// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(users, ['user', 'age'], ['asc', 'desc']);
// → objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]
_.partition(collection, [predicate=_.identity])
Creates an array of elements split into two groups, the first of which
contains elements predicate
returns truthy for, the second of which
contains elements predicate
returns falsey for. The predicate is
invoked with one argument: (value).
3.0.0
collection
(Array|Object): The collection to iterate over.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the array of grouped elements.
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': true },
{ 'user': 'pebbles', 'age': 1, 'active': false }
];
_.partition(users, function(o) { return o.active; });
// → objects for [['fred'], ['barney', 'pebbles']]
// The `_.matches` iteratee shorthand.
_.partition(users, { 'age': 1, 'active': false });
// → objects for [['pebbles'], ['barney', 'fred']]
// The `_.matchesProperty` iteratee shorthand.
_.partition(users, ['active', false]);
// → objects for [['barney', 'pebbles'], ['fred']]
// The `_.property` iteratee shorthand.
_.partition(users, 'active');
// → objects for [['fred'], ['barney', 'pebbles']]
_.reduce(collection, [iteratee=_.identity], [accumulator])
Reduces collection
to a value which is the accumulated result of running
each element in collection
thru iteratee
, where each successive
invocation is supplied the return value of the previous. If accumulator
is not given, the first element of collection
is used as the initial
value. The iteratee is invoked with four arguments:
(accumulator, value, index|key, collection).
Many lodash methods are guarded to work as iteratees for methods like
_.reduce
, _.reduceRight
, and _.transform
.
The guarded methods are:
assign
, defaults
, defaultsDeep
, includes
, merge
, orderBy
,
and sortBy
0.1.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.[accumulator]
(*): The initial value.(*): Returns the accumulated value.
_.reduce([1, 2], function(sum, n) {
return sum + n;
}, 0);
// → 3
_.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
(result[value] || (result[value] = [])).push(key);
return result;
}, {});
// → { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)
_.reduceRight(collection, [iteratee=_.identity], [accumulator])
This method is like _.reduce
except that it iterates over elements of
collection
from right to left.
0.1.0
collection
(Array|Object): The collection to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.[accumulator]
(*): The initial value.(*): Returns the accumulated value.
var array = [[0, 1], [2, 3], [4, 5]];
_.reduceRight(array, function(flattened, other) {
return flattened.concat(other);
}, []);
// → [4, 5, 2, 3, 0, 1]
_.reject(collection, [predicate=_.identity])
The opposite of _.filter
; this method returns the elements of collection
that predicate
does not return truthy for.
0.1.0
collection
(Array|Object): The collection to iterate over.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Array): Returns the new filtered array.
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': true }
];
_.reject(users, function(o) { return !o.active; });
// → objects for ['fred']
// The `_.matches` iteratee shorthand.
_.reject(users, { 'age': 40, 'active': true });
// → objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.reject(users, ['active', false]);
// → objects for ['fred']
// The `_.property` iteratee shorthand.
_.reject(users, 'active');
// → objects for ['barney']
_.sample(collection)
Gets a random element from collection
.
2.0.0
collection
(Array|Object): The collection to sample.(*): Returns the random element.
_.sample([1, 2, 3, 4]);
// → 2
_.sampleSize(collection, [n=1])
Gets n
random elements at unique keys from collection
up to the
size of collection
.
4.0.0
collection
(Array|Object): The collection to sample.[n=1]
(number): The number of elements to sample.(Array): Returns the random elements.
_.sampleSize([1, 2, 3], 2);
// → [3, 1]
_.sampleSize([1, 2, 3], 4);
// → [2, 3, 1]
_.shuffle(collection)
Creates an array of shuffled values, using a version of the Fisher-Yates shuffle.
0.1.0
collection
(Array|Object): The collection to shuffle.(Array): Returns the new shuffled array.
_.shuffle([1, 2, 3, 4]);
// → [4, 1, 3, 2]
_.size(collection)
Gets the size of collection
by returning its length for array-like
values or the number of own enumerable string keyed properties for objects.
0.1.0
collection
(Array|Object): The collection to inspect.(number): Returns the collection size.
_.size([1, 2, 3]);
// → 3
_.size({ 'a': 1, 'b': 2 });
// → 2
_.size('pebbles');
// → 7
_.some(collection, [predicate=_.identity])
Checks if predicate
returns truthy for any element of collection
.
Iteration is stopped once predicate
returns truthy. The predicate is
invoked with three arguments: (value, index|key, collection).
0.1.0
collection
(Array|Object): The collection to iterate over.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(boolean): Returns true
if any element passes the predicate check, else false
.
_.some([null, 0, 'yes', false], Boolean);
// → true
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false }
];
// The `_.matches` iteratee shorthand.
_.some(users, { 'user': 'barney', 'active': false });
// → false
// The `_.matchesProperty` iteratee shorthand.
_.some(users, ['active', false]);
// → true
// The `_.property` iteratee shorthand.
_.some(users, 'active');
// → true
_.sortBy(collection, [iteratees=[_.identity]])
Creates an array of elements, sorted in ascending order by the results of running each element in a collection thru each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
0.1.0
collection
(Array|Object): The collection to iterate over.[iteratees=[_.identity]]
(…(Array|Array[]|Function|Function[]|Object|Object[]|string|string[])): The iteratees to sort by.(Array): Returns the new sorted array.
var users = [
{ 'user': 'fred', 'age': 48 },
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 },
{ 'user': 'barney', 'age': 34 }
];
_.sortBy(users, function(o) { return o.user; });
// → objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]
_.sortBy(users, ['user', 'age']);
// → objects for [['barney', 34], ['barney', 36], ['fred', 40], ['fred', 48]]
_.sortBy(users, 'user', function(o) {
return Math.floor(o.age / 10);
});
// → objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 40]]
“Date” Methods
_.now()
Gets the timestamp of the number of milliseconds that have elapsed since
the Unix epoch (1 January 1970 00
:00:00 UTC).
2.4.0
(number): Returns the timestamp.
_.defer(function(stamp) {
console.log(_.now() - stamp);
}, _.now());
// → Logs the number of milliseconds it took for the deferred function to be invoked.
“Function” Methods
_.after(n, func)
The opposite of _.before
; this method creates a function that invokes
func
once it’s called n
or more times.
0.1.0
n
(number): The number of calls before func
is invoked.func
(Function): The function to restrict.(Function): Returns the new restricted function.
var saves = ['profile', 'settings'];
var done = _.after(saves.length, function() {
console.log('done saving!');
});
_.forEach(saves, function(type) {
asyncSave({ 'type': type, 'complete': done });
});
// → Logs 'done saving!' after the two async saves have completed.
_.ary(func, [n=func.length])
Creates a function that invokes func
, with up to n
arguments,
ignoring any additional arguments.
3.0.0
func
(Function): The function to cap arguments for.[n=func.length]
(number): The arity cap.(Function): Returns the new function.
_.map(['6', '8', '10'], _.ary(parseInt, 1));
// → [6, 8, 10]
_.before(n, func)
Creates a function that invokes func
, with the this
binding and arguments
of the created function, while it’s called less than n
times. Subsequent
calls to the created function return the result of the last func
invocation.
3.0.0
n
(number): The number of calls at which func
is no longer invoked.func
(Function): The function to restrict.(Function): Returns the new restricted function.
jQuery(element).on('click', _.before(5, addContactToList));
// → allows adding up to 4 contacts to the list
_.bind(func, thisArg, [partials])
Creates a function that invokes func
with the this
binding of thisArg
and partials
prepended to the arguments it receives.
The _.bind.placeholder
value, which defaults to _
in monolithic builds,
may be used as a placeholder for partially applied arguments.
Note: Unlike native Function#bind
this method doesn’t set the "length"
property of bound functions.
0.1.0
func
(Function): The function to bind.thisArg
(*): The this
binding of func
.[partials]
(…*): The arguments to be partially applied.(Function): Returns the new bound function.
var greet = function(greeting, punctuation) {
return greeting + ' ' + this.user + punctuation;
};
var object = { 'user': 'fred' };
var bound = _.bind(greet, object, 'hi');
bound('!');
// → 'hi fred!'
// Bound with placeholders.
var bound = _.bind(greet, object, _, '!');
bound('hi');
// → 'hi fred!'
_.bindKey(object, key, [partials])
Creates a function that invokes the method at object[key]
with partials
prepended to the arguments it receives.
This method differs from _.bind
by allowing bound functions to reference
methods that may be redefined or don’t yet exist. See
Peter Michaux’s article
for more details.
The _.bindKey.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for partially applied arguments.
0.10.0
object
(Object): The object to invoke the method on.key
(string): The key of the method.[partials]
(…*): The arguments to be partially applied.(Function): Returns the new bound function.
var object = {
'user': 'fred',
'greet': function(greeting, punctuation) {
return greeting + ' ' + this.user + punctuation;
}
};
var bound = _.bindKey(object, 'greet', 'hi');
bound('!');
// → 'hi fred!'
object.greet = function(greeting, punctuation) {
return greeting + 'ya ' + this.user + punctuation;
};
bound('!');
// → 'hiya fred!'
// Bound with placeholders.
var bound = _.bindKey(object, 'greet', _, '!');
bound('hi');
// → 'hiya fred!'
_.curry(func, [arity=func.length])
Creates a function that accepts arguments of func
and either invokes
func
returning its result, if at least arity
number of arguments have
been provided, or returns a function that accepts the remaining func
arguments, and so on. The arity of func
may be specified if func.length
is not sufficient.
The _.curry.placeholder
value, which defaults to _
in monolithic builds,
may be used as a placeholder for provided arguments.
Note: This method doesn’t set the "length" property of curried functions.
2.0.0
func
(Function): The function to curry.[arity=func.length]
(number): The arity of func
.(Function): Returns the new curried function.
var abc = function(a, b, c) {
return [a, b, c];
};
var curried = _.curry(abc);
curried(1)(2)(3);
// → [1, 2, 3]
curried(1, 2)(3);
// → [1, 2, 3]
curried(1, 2, 3);
// → [1, 2, 3]
// Curried with placeholders.
curried(1)(_, 3)(2);
// → [1, 2, 3]
_.curryRight(func, [arity=func.length])
This method is like _.curry
except that arguments are applied to func
in the manner of _.partialRight
instead of _.partial
.
The _.curryRight.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for provided arguments.
Note: This method doesn’t set the "length" property of curried functions.
3.0.0
func
(Function): The function to curry.[arity=func.length]
(number): The arity of func
.(Function): Returns the new curried function.
var abc = function(a, b, c) {
return [a, b, c];
};
var curried = _.curryRight(abc);
curried(3)(2)(1);
// → [1, 2, 3]
curried(2, 3)(1);
// → [1, 2, 3]
curried(1, 2, 3);
// → [1, 2, 3]
// Curried with placeholders.
curried(3)(1, _)(2);
// → [1, 2, 3]
_.debounce(func, [wait=0], [options={}], [options.leading=false], [options.maxWait], [options.trailing=true])
Creates a debounced function that delays invoking func
until after wait
milliseconds have elapsed since the last time the debounced function was
invoked. The debounced function comes with a cancel
method to cancel
delayed func
invocations and a flush
method to immediately invoke them.
Provide an options object to indicate whether func
should be invoked on
the leading and/or trailing edge of the wait
timeout. The func
is invoked
with the last arguments provided to the debounced function. Subsequent calls
to the debounced function return the result of the last func
invocation.
Note: If leading
and trailing
options are true
, func
is invoked
on the trailing edge of the timeout only if the debounced function is
invoked more than once during the wait
timeout.
See David Corbacho’s article
for details over the differences between _.debounce
and _.throttle
.
0.1.0
func
(Function): The function to debounce.[wait=0]
(number): The number of milliseconds to delay.[options={}]
(Object): The options object.[options.leading=false]
(boolean): Specify invoking on the leading edge of the timeout.[options.maxWait]
(number): The maximum time func
is allowed to be delayed before it’s invoked.[options.trailing=true]
(boolean): Specify invoking on the trailing edge of the timeout.(Function): Returns the new debounced function.
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(calculateLayout, 150));
// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce(sendMail, 300, {
'leading': true,
'trailing': false
}));
// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce(batchLog, 250, { 'maxWait': 1000 });
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);
// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);
_.defer(func, [args])
Defers invoking the func
until the current call stack has cleared. Any
additional arguments are provided to func
when it’s invoked.
0.1.0
func
(Function): The function to defer.[args]
(…*): The arguments to invoke func
with.(number): Returns the timer id.
_.defer(function(text) {
console.log(text);
}, 'deferred');
// → Logs 'deferred' after one or more milliseconds.
_.delay(func, wait, [args])
Invokes func
after wait
milliseconds. Any additional arguments are
provided to func
when it’s invoked.
0.1.0
func
(Function): The function to delay.wait
(number): The number of milliseconds to delay invocation.[args]
(…*): The arguments to invoke func
with.(number): Returns the timer id.
_.delay(function(text) {
console.log(text);
}, 1000, 'later');
// → Logs 'later' after one second.
_.flip(func)
Creates a function that invokes func
with arguments reversed.
4.0.0
func
(Function): The function to flip arguments for.(Function): Returns the new function.
var flipped = _.flip(function() {
return _.toArray(arguments);
});
flipped('a', 'b', 'c', 'd');
// → ['d', 'c', 'b', 'a']
_.memoize(func, [resolver])
Creates a function that memoizes the result of func
. If resolver
is
provided, it determines the cache key for storing the result based on the
arguments provided to the memoized function. By default, the first argument
provided to the memoized function is used as the map cache key. The func
is invoked with the this
binding of the memoized function.
Note: The cache is exposed as the cache
property on the memoized
function. Its creation may be customized by replacing the _.memoize.Cache
constructor with one whose instances implement the
Map
method interface of delete
, get
, has
, and set
.
0.1.0
func
(Function): The function to have its output memoized.[resolver]
(Function): The function to resolve the cache key.(Function): Returns the new memoizing function.
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };
var values = _.memoize(_.values);
values(object);
// → [1, 2]
values(other);
// → [3, 4]
object.a = 2;
values(object);
// → [1, 2]
// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// → ['a', 'b']
// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;
_.negate(predicate)
Creates a function that negates the result of the predicate func
. The
func
predicate is invoked with the this
binding and arguments of the
created function.
3.0.0
predicate
(Function): The predicate to negate.(Function): Returns the new function.
function isEven(n) {
return n % 2 == 0;
}
_.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
// → [1, 3, 5]
_.once(func)
Creates a function that is restricted to invoking func
once. Repeat calls
to the function return the value of the first invocation. The func
is
invoked with the this
binding and arguments of the created function.
0.1.0
func
(Function): The function to restrict.(Function): Returns the new restricted function.
var initialize = _.once(createApplication);
initialize();
initialize();
// `initialize` invokes `createApplication` once
_.overArgs(func)
Creates a function that invokes func
with arguments transformed by
corresponding transforms
.
4.0.0
func
(Function): The function to wrap.(Function): Returns the new function.
function doubled(n) {
return n * 2;
}
function square(n) {
return n * n;
}
var func = _.overArgs(function(x, y) {
return [x, y];
}, square, doubled);
func(9, 3);
// → [81, 6]
func(10, 5);
// → [100, 10]
_.partial(func, [partials])
Creates a function that invokes func
with partials
prepended to the
arguments it receives. This method is like _.bind
except it does not
alter the this
binding.
The _.partial.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for partially applied arguments.
Note: This method doesn’t set the "length" property of partially
applied functions.
0.2.0
func
(Function): The function to partially apply arguments to.[partials]
(…*): The arguments to be partially applied.(Function): Returns the new partially applied function.
var greet = function(greeting, name) {
return greeting + ' ' + name;
};
var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// → 'hello fred'
// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// → 'hi fred'
_.partialRight(func, [partials])
This method is like _.partial
except that partially applied arguments
are appended to the arguments it receives.
The _.partialRight.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for partially applied arguments.
Note: This method doesn’t set the "length" property of partially
applied functions.
1.0.0
func
(Function): The function to partially apply arguments to.[partials]
(…*): The arguments to be partially applied.(Function): Returns the new partially applied function.
var greet = function(greeting, name) {
return greeting + ' ' + name;
};
var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// → 'hi fred'
// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// → 'hello fred'
_.rearg(func, indexes)
Creates a function that invokes func
with arguments arranged according
to the specified indexes
where the argument value at the first index is
provided as the first argument, the argument value at the second index is
provided as the second argument, and so on.
3.0.0
func
(Function): The function to rearrange arguments for.indexes
(…(number|number[])): The arranged argument indexes.(Function): Returns the new function.
var rearged = _.rearg(function(a, b, c) {
return [a, b, c];
}, 2, 0, 1);
rearged('b', 'c', 'a')
// → ['a', 'b', 'c']
_.rest(func, [start=func.length-1])
Creates a function that invokes func
with the this
binding of the
created function and arguments from start
and beyond provided as
an array.
Note: This method is based on the
rest parameter.
4.0.0
func
(Function): The function to apply a rest parameter to.[start=func.length-1]
(number): The start position of the rest parameter.(Function): Returns the new function.
var say = _.rest(function(what, names) {
return what + ' ' + _.initial(names).join(', ') +
(_.size(names) > 1 ? ', & ' : '') + _.last(names);
});
say('hello', 'fred', 'barney', 'pebbles');
// → 'hello fred, barney, & pebbles'
_.spread(func, [start=0])
Creates a function that invokes func
with the this
binding of the
create function and an array of arguments much like
Function#apply
.
Note: This method is based on the
spread operator.
3.2.0
func
(Function): The function to spread arguments over.[start=0]
(number): The start position of the spread.(Function): Returns the new function.
var say = _.spread(function(who, what) {
return who + ' says ' + what;
});
say(['fred', 'hello']);
// → 'fred says hello'
var numbers = Promise.all([
Promise.resolve(40),
Promise.resolve(36)
]);
numbers.then(_.spread(function(x, y) {
return x + y;
}));
// → a Promise of 76
_.throttle(func, [wait=0], [options={}], [options.leading=true], [options.trailing=true])
Creates a throttled function that only invokes func
at most once per
every wait
milliseconds. The throttled function comes with a cancel
method to cancel delayed func
invocations and a flush
method to
immediately invoke them. Provide an options object to indicate whether
func
should be invoked on the leading and/or trailing edge of the wait
timeout. The func
is invoked with the last arguments provided to the
throttled function. Subsequent calls to the throttled function return the
result of the last func
invocation.
Note: If leading
and trailing
options are true
, func
is
invoked on the trailing edge of the timeout only if the throttled function
is invoked more than once during the wait
timeout.
See David Corbacho’s article
for details over the differences between _.throttle
and _.debounce
.
0.1.0
func
(Function): The function to throttle.[wait=0]
(number): The number of milliseconds to throttle invocations to.[options={}]
(Object): The options object.[options.leading=true]
(boolean): Specify invoking on the leading edge of the timeout.[options.trailing=true]
(boolean): Specify invoking on the trailing edge of the timeout.(Function): Returns the new throttled function.
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(updatePosition, 100));
// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
jQuery(element).on('click', throttled);
// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);
_.unary(func)
Creates a function that accepts up to one argument, ignoring any additional arguments.
4.0.0
func
(Function): The function to cap arguments for.(Function): Returns the new function.
_.map(['6', '8', '10'], _.unary(parseInt));
// → [6, 8, 10]
_.wrap(value, [wrapper=identity])
Creates a function that provides value
to the wrapper function as its
first argument. Any additional arguments provided to the function are
appended to those provided to the wrapper function. The wrapper is invoked
with the this
binding of the created function.
0.1.0
value
(*): The value to wrap.[wrapper=identity]
(Function): The wrapper function.(Function): Returns the new function.
var p = _.wrap(_.escape, function(func, text) {
return '<p>' + func(text) + '<p>';
});
p('fred, barney, & pebbles');
// → '<p>fred, barney, & pebbles<p>'
“Lang” Methods
_.castArray(value)
Casts value
as an array if it’s not one.
4.4.0
value
(*): The value to inspect.(Array): Returns the cast array.
_.castArray(1);
// → [1]
_.castArray({ 'a': 1 });
// → [{ 'a': 1 }]
_.castArray('abc');
// → ['abc']
_.castArray(null);
// → [null]
_.castArray(undefined);
// → [undefined]
_.castArray();
// → []
var array = [1, 2, 3];
console.log(_.castArray(array) === array);
// → true
_.clone(value)
Creates a shallow clone of value
.
Note: This method is loosely based on the
structured clone algorithm
and supports cloning arrays, array buffers, booleans, date objects, maps,
numbers, Object
objects, regexes, sets, strings, symbols, and typed
arrays. The own enumerable properties of arguments
objects are cloned
as plain objects. An empty object is returned for uncloneable values such
as error objects, functions, DOM nodes, and WeakMaps.
0.1.0
value
(*): The value to clone.(*): Returns the cloned value.
var objects = [{ 'a': 1 }, { 'b': 2 }];
var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// → true
_.cloneDeep(value)
This method is like _.clone
except that it recursively clones value
.
1.0.0
value
(*): The value to recursively clone.(*): Returns the deep cloned value.
var objects = [{ 'a': 1 }, { 'b': 2 }];
var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// → false
_.cloneDeepWith(value, [customizer])
This method is like _.cloneWith
except that it recursively clones value
.
4.0.0
value
(*): The value to recursively clone.[customizer]
(Function): The function to customize cloning.(*): Returns the deep cloned value.
function customizer(value) {
if (_.isElement(value)) {
return value.cloneNode(true);
}
}
var el = _.cloneDeepWith(document.body, customizer);
console.log(el === document.body);
// → false
console.log(el.nodeName);
// → 'BODY'
console.log(el.childNodes.length);
// → 20
_.cloneWith(value, [customizer])
This method is like _.clone
except that it accepts customizer
which
is invoked to produce the cloned value. If customizer
returns undefined
,
cloning is handled by the method instead. The customizer
is invoked with
up to four arguments; (value [, index|key, object, stack]).
4.0.0
value
(*): The value to clone.[customizer]
(Function): The function to customize cloning.(*): Returns the cloned value.
function customizer(value) {
if (_.isElement(value)) {
return value.cloneNode(false);
}
}
var el = _.cloneWith(document.body, customizer);
console.log(el === document.body);
// → false
console.log(el.nodeName);
// → 'BODY'
console.log(el.childNodes.length);
// → 0
_.eq(value, other)
Performs a
SameValueZero
comparison between two values to determine if they are equivalent.
4.0.0
value
(*): The value to compare.other
(*): The other value to compare.(boolean): Returns true
if the values are equivalent, else false
.
var object = { 'user': 'fred' };
var other = { 'user': 'fred' };
_.eq(object, object);
// → true
_.eq(object, other);
// → false
_.eq('a', 'a');
// → true
_.eq('a', Object('a'));
// → false
_.eq(NaN, NaN);
// → true
_.gt(value, other)
Checks if value
is greater than other
.
3.9.0
value
(*): The value to compare.other
(*): The other value to compare.(boolean): Returns true
if value
is greater than other
, else false
.
_.gt(3, 1);
// → true
_.gt(3, 3);
// → false
_.gt(1, 3);
// → false
_.gte(value, other)
Checks if value
is greater than or equal to other
.
3.9.0
value
(*): The value to compare.other
(*): The other value to compare.(boolean): Returns true
if value
is greater than or equal to other
, else false
.
_.gte(3, 1);
// → true
_.gte(3, 3);
// → true
_.gte(1, 3);
// → false
_.isArguments(value)
Checks if value
is likely an arguments
object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isArguments(function() { return arguments; }());
// → true
_.isArguments([1, 2, 3]);
// → false
_.isArray(value)
Checks if value
is classified as an Array
object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isArray([1, 2, 3]);
// → true
_.isArray(document.body.children);
// → false
_.isArray('abc');
// → false
_.isArray(_.noop);
// → false
_.isArrayBuffer(value)
Checks if value
is classified as an ArrayBuffer
object.
4.3.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isArrayBuffer(new ArrayBuffer(2));
// → true
_.isArrayBuffer(new Array(2));
// → false
_.isArrayLike(value)
Checks if value
is array-like. A value is considered array-like if it’s
not a function and has a value.length
that’s an integer greater than or
equal to 0
and less than or equal to Number.MAX_SAFE_INTEGER
.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is array-like, else false
.
_.isArrayLike([1, 2, 3]);
// → true
_.isArrayLike(document.body.children);
// → true
_.isArrayLike('abc');
// → true
_.isArrayLike(_.noop);
// → false
_.isArrayLikeObject(value)
This method is like _.isArrayLike
except that it also checks if value
is an object.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is an array-like object, else false
.
_.isArrayLikeObject([1, 2, 3]);
// → true
_.isArrayLikeObject(document.body.children);
// → true
_.isArrayLikeObject('abc');
// → false
_.isArrayLikeObject(_.noop);
// → false
_.isBoolean(value)
Checks if value
is classified as a boolean primitive or object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isBoolean(false);
// → true
_.isBoolean(null);
// → false
_.isBuffer(value)
Checks if value
is a buffer.
4.3.0
value
(*): The value to check.(boolean): Returns true
if value
is a buffer, else false
.
_.isBuffer(new Buffer(2));
// → true
_.isBuffer(new Uint8Array(2));
// → false
_.isDate(value)
Checks if value
is classified as a Date
object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isDate(new Date);
// → true
_.isDate('Mon April 23 2012');
// → false
_.isElement(value)
Checks if value
is likely a DOM element.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is a DOM element, else false
.
_.isElement(document.body);
// → true
_.isElement('<body>');
// → false
_.isEmpty(value)
Checks if value
is an empty object, collection, map, or set.
Objects are considered empty if they have no own enumerable string keyed
properties.
Array-like values such as arguments
objects, arrays, buffers, strings, or
jQuery-like collections are considered empty if they have a length
of 0
.
Similarly, maps and sets are considered empty if they have a size
of 0
.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is empty, else false
.
_.isEmpty(null);
// → true
_.isEmpty(true);
// → true
_.isEmpty(1);
// → true
_.isEmpty([1, 2, 3]);
// → false
_.isEmpty({ 'a': 1 });
// → false
_.isEqual(value, other)
Performs a deep comparison between two values to determine if they are
equivalent.
Note: This method supports comparing arrays, array buffers, booleans,
date objects, error objects, maps, numbers, Object
objects, regexes,
sets, strings, symbols, and typed arrays. Object
objects are compared
by their own, not inherited, enumerable properties. Functions and DOM
nodes are not supported.
0.1.0
value
(*): The value to compare.other
(*): The other value to compare.(boolean): Returns true
if the values are equivalent, else false
.
var object = { 'user': 'fred' };
var other = { 'user': 'fred' };
_.isEqual(object, other);
// → true
object === other;
// → false
_.isEqualWith(value, other, [customizer])
This method is like _.isEqual
except that it accepts customizer
which
is invoked to compare values. If customizer
returns undefined
, comparisons
are handled by the method instead. The customizer
is invoked with up to
six arguments: (objValue, othValue [, index|key, object, other, stack]).
4.0.0
value
(*): The value to compare.other
(*): The other value to compare.[customizer]
(Function): The function to customize comparisons.(boolean): Returns true
if the values are equivalent, else false
.
function isGreeting(value) {
return /^h(?:i|ello)$/.test(value);
}
function customizer(objValue, othValue) {
if (isGreeting(objValue) && isGreeting(othValue)) {
return true;
}
}
var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];
_.isEqualWith(array, other, customizer);
// → true
_.isError(value)
Checks if value
is an Error
, EvalError
, RangeError
, ReferenceError
,
SyntaxError
, TypeError
, or URIError
object.
3.0.0
value
(*): The value to check.(boolean): Returns true
if value
is an error object, else false
.
_.isError(new Error);
// → true
_.isError(Error);
// → false
_.isFinite(value)
Checks if value
is a finite primitive number.
Note: This method is based on
Number.isFinite
.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is a finite number, else false
.
_.isFinite(3);
// → true
_.isFinite(Number.MAX_VALUE);
// → true
_.isFinite(3.14);
// → true
_.isFinite(Infinity);
// → false
_.isFunction(value)
Checks if value
is classified as a Function
object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isFunction(_);
// → true
_.isFunction(/abc/);
// → false
_.isInteger(value)
Checks if value
is an integer.
Note: This method is based on
Number.isInteger
.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is an integer, else false
.
_.isInteger(3);
// → true
_.isInteger(Number.MIN_VALUE);
// → false
_.isInteger(Infinity);
// → false
_.isInteger('3');
// → false
_.isLength(value)
Checks if value
is a valid array-like length.
Note: This function is loosely based on
ToLength
.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is a valid length, else false
.
_.isLength(3);
// → true
_.isLength(Number.MIN_VALUE);
// → false
_.isLength(Infinity);
// → false
_.isLength('3');
// → false
_.isMap(value)
Checks if value
is classified as a Map
object.
4.3.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isMap(new Map);
// → true
_.isMap(new WeakMap);
// → false
_.isMatch(object, source)
Performs a partial deep comparison between object
and source
to
determine if object
contains equivalent property values. This method is
equivalent to a _.matches
function when source
is partially applied.
Note: This method supports comparing the same values as _.isEqual
.
3.0.0
object
(Object): The object to inspect.source
(Object): The object of property values to match.(boolean): Returns true
if object
is a match, else false
.
var object = { 'user': 'fred', 'age': 40 };
_.isMatch(object, { 'age': 40 });
// → true
_.isMatch(object, { 'age': 36 });
// → false
_.isMatchWith(object, source, [customizer])
This method is like _.isMatch
except that it accepts customizer
which
is invoked to compare values. If customizer
returns undefined
, comparisons
are handled by the method instead. The customizer
is invoked with five
arguments: (objValue, srcValue, index|key, object, source).
4.0.0
object
(Object): The object to inspect.source
(Object): The object of property values to match.[customizer]
(Function): The function to customize comparisons.(boolean): Returns true
if object
is a match, else false
.
function isGreeting(value) {
return /^h(?:i|ello)$/.test(value);
}
function customizer(objValue, srcValue) {
if (isGreeting(objValue) && isGreeting(srcValue)) {
return true;
}
}
var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };
_.isMatchWith(object, source, customizer);
// → true
_.isNaN(value)
Checks if value
is NaN
.
Note: This method is based on
Number.isNaN
and is not the same as
global isNaN
which returns true
for
undefined
and other non-number values.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is NaN
, else false
.
_.isNaN(NaN);
// → true
_.isNaN(new Number(NaN));
// → true
isNaN(undefined);
// → true
_.isNaN(undefined);
// → false
_.isNative(value)
Checks if value
is a native function.
3.0.0
value
(*): The value to check.(boolean): Returns true
if value
is a native function, else false
.
_.isNative(Array.prototype.push);
// → true
_.isNative(_);
// → false
_.isNil(value)
Checks if value
is null
or undefined
.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is nullish, else false
.
_.isNil(null);
// → true
_.isNil(void 0);
// → true
_.isNil(NaN);
// → false
_.isNull(value)
Checks if value
is null
.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is null
, else false
.
_.isNull(null);
// → true
_.isNull(void 0);
// → false
_.isNumber(value)
Checks if value
is classified as a Number
primitive or object.
Note: To exclude Infinity
, -Infinity
, and NaN
, which are
classified as numbers, use the _.isFinite
method.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isNumber(3);
// → true
_.isNumber(Number.MIN_VALUE);
// → true
_.isNumber(Infinity);
// → true
_.isNumber('3');
// → false
_.isObject(value)
Checks if value
is the
language type
of Object
. (e.g. arrays, functions, objects, regexes, new Number(0)
, and new String('')
)
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is an object, else false
.
_.isObject({});
// → true
_.isObject([1, 2, 3]);
// → true
_.isObject(_.noop);
// → true
_.isObject(null);
// → false
_.isObjectLike(value)
Checks if value
is object-like. A value is object-like if it’s not null
and has a typeof
result of "object".
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is object-like, else false
.
_.isObjectLike({});
// → true
_.isObjectLike([1, 2, 3]);
// → true
_.isObjectLike(_.noop);
// → false
_.isObjectLike(null);
// → false
_.isPlainObject(value)
Checks if value
is a plain object, that is, an object created by the
Object
constructor or one with a [[Prototype]]
of null
.
0.8.0
value
(*): The value to check.(boolean): Returns true
if value
is a plain object, else false
.
function Foo() {
this.a = 1;
}
_.isPlainObject(new Foo);
// → false
_.isPlainObject([1, 2, 3]);
// → false
_.isPlainObject({ 'x': 0, 'y': 0 });
// → true
_.isPlainObject(Object.create(null));
// → true
_.isRegExp(value)
Checks if value
is classified as a RegExp
object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isRegExp(/abc/);
// → true
_.isRegExp('/abc/');
// → false
_.isSafeInteger(value)
Checks if value
is a safe integer. An integer is safe if it’s an IEEE-754
double precision number which isn’t the result of a rounded unsafe integer.
Note: This method is based on
Number.isSafeInteger
.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is a safe integer, else false
.
_.isSafeInteger(3);
// → true
_.isSafeInteger(Number.MIN_VALUE);
// → false
_.isSafeInteger(Infinity);
// → false
_.isSafeInteger('3');
// → false
_.isSet(value)
Checks if value
is classified as a Set
object.
4.3.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isSet(new Set);
// → true
_.isSet(new WeakSet);
// → false
_.isString(value)
Checks if value
is classified as a String
primitive or object.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isString('abc');
// → true
_.isString(1);
// → false
_.isSymbol(value)
Checks if value
is classified as a Symbol
primitive or object.
4.0.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isSymbol(Symbol.iterator);
// → true
_.isSymbol('abc');
// → false
_.isTypedArray(value)
Checks if value
is classified as a typed array.
3.0.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isTypedArray(new Uint8Array);
// → true
_.isTypedArray([]);
// → false
_.isUndefined(value)
Checks if value
is undefined
.
0.1.0
value
(*): The value to check.(boolean): Returns true
if value
is undefined
, else false
.
_.isUndefined(void 0);
// → true
_.isUndefined(null);
// → false
_.isWeakMap(value)
Checks if value
is classified as a WeakMap
object.
4.3.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isWeakMap(new WeakMap);
// → true
_.isWeakMap(new Map);
// → false
_.isWeakSet(value)
Checks if value
is classified as a WeakSet
object.
4.3.0
value
(*): The value to check.(boolean): Returns true
if value
is correctly classified, else false
.
_.isWeakSet(new WeakSet);
// → true
_.isWeakSet(new Set);
// → false
_.lt(value, other)
Checks if value
is less than other
.
3.9.0
value
(*): The value to compare.other
(*): The other value to compare.(boolean): Returns true
if value
is less than other
, else false
.
_.lt(1, 3);
// → true
_.lt(3, 3);
// → false
_.lt(3, 1);
// → false
_.lte(value, other)
Checks if value
is less than or equal to other
.
3.9.0
value
(*): The value to compare.other
(*): The other value to compare.(boolean): Returns true
if value
is less than or equal to other
, else false
.
_.lte(1, 3);
// → true
_.lte(3, 3);
// → true
_.lte(3, 1);
// → false
_.toArray(value)
Converts value
to an array.
0.1.0
value
(*): The value to convert.(Array): Returns the converted array.
_.toArray({ 'a': 1, 'b': 2 });
// → [1, 2]
_.toArray('abc');
// → ['a', 'b', 'c']
_.toArray(1);
// → []
_.toArray(null);
// → []
_.toInteger(value)
Converts value
to an integer.
Note: This function is loosely based on
ToInteger
.
4.0.0
value
(*): The value to convert.(number): Returns the converted integer.
_.toInteger(3);
// → 3
_.toInteger(Number.MIN_VALUE);
// → 0
_.toInteger(Infinity);
// → 1.7976931348623157e+308
_.toInteger('3');
// → 3
_.toLength(value)
Converts value
to an integer suitable for use as the length of an
array-like object.
Note: This method is based on
ToLength
.
4.0.0
value
(*): The value to convert.(number): Returns the converted integer.
_.toLength(3);
// → 3
_.toLength(Number.MIN_VALUE);
// → 0
_.toLength(Infinity);
// → 4294967295
_.toLength('3');
// → 3
_.toNumber(value)
Converts value
to a number.
4.0.0
value
(*): The value to process.(number): Returns the number.
_.toNumber(3);
// → 3
_.toNumber(Number.MIN_VALUE);
// → 5e-324
_.toNumber(Infinity);
// → Infinity
_.toNumber('3');
// → 3
_.toPlainObject(value)
Converts value
to a plain object flattening inherited enumerable string
keyed properties of value
to own properties of the plain object.
3.0.0
value
(*): The value to convert.(Object): Returns the converted plain object.
function Foo() {
this.b = 2;
}
Foo.prototype.c = 3;
_.assign({ 'a': 1 }, new Foo);
// → { 'a': 1, 'b': 2 }
_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// → { 'a': 1, 'b': 2, 'c': 3 }
_.toSafeInteger(value)
Converts value
to a safe integer. A safe integer can be compared and
represented correctly.
4.0.0
value
(*): The value to convert.(number): Returns the converted integer.
_.toSafeInteger(3);
// → 3
_.toSafeInteger(Number.MIN_VALUE);
// → 0
_.toSafeInteger(Infinity);
// → 9007199254740991
_.toSafeInteger('3');
// → 3
_.toString(value)
Converts value
to a string. An empty string is returned for null
and undefined
values. The sign of -0
is preserved.
4.0.0
value
(*): The value to process.(string): Returns the string.
_.toString(null);
// → ''
_.toString(-0);
// → '-0'
_.toString([1, 2, 3]);
// → '1,2,3'
“Math” Methods
_.add(augend, addend)
Adds two numbers.
3.4.0
augend
(number): The first number in an addition.addend
(number): The second number in an addition.(number): Returns the total.
_.add(6, 4);
// → 10
_.ceil(number, [precision=0])
Computes number
rounded up to precision
.
3.10.0
number
(number): The number to round up.[precision=0]
(number): The precision to round up to.(number): Returns the rounded up number.
_.ceil(4.006);
// → 5
_.ceil(6.004, 2);
// → 6.01
_.ceil(6040, -2);
// → 6100
_.divide(dividend, divisor)
Divide two numbers.
4.7.0
dividend
(number): The first number in a division.divisor
(number): The second number in a division.(number): Returns the quotient.
_.divide(6, 4);
// → 1.5
_.floor(number, [precision=0])
Computes number
rounded down to precision
.
3.10.0
number
(number): The number to round down.[precision=0]
(number): The precision to round down to.(number): Returns the rounded down number.
_.floor(4.006);
// → 4
_.floor(0.046, 2);
// → 0.04
_.floor(4060, -2);
// → 4000
_.max(array)
Computes the maximum value of array
. If array
is empty or falsey,
undefined
is returned.
0.1.0
array
(Array): The array to iterate over.(*): Returns the maximum value.
_.max([4, 2, 8, 6]);
// → 8
_.max([]);
// → undefined
_.maxBy(array, [iteratee=_.identity])
This method is like _.max
except that it accepts iteratee
which is
invoked for each element in array
to generate the criterion by which
the value is ranked. The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The array to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(*): Returns the maximum value.
var objects = [{ 'n': 1 }, { 'n': 2 }];
_.maxBy(objects, function(o) { return o.n; });
// → { 'n': 2 }
// The `_.property` iteratee shorthand.
_.maxBy(objects, 'n');
// → { 'n': 2 }
_.mean(array)
Computes the mean of the values in array
.
4.0.0
array
(Array): The array to iterate over.(number): Returns the mean.
_.mean([4, 2, 8, 6]);
// → 5
_.meanBy(array, [iteratee=_.identity])
This method is like _.mean
except that it accepts iteratee
which is
invoked for each element in array
to generate the value to be averaged.
The iteratee is invoked with one argument: (value).
4.7.0
array
(Array): The array to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(number): Returns the mean.
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];
_.meanBy(objects, function(o) { return o.n; });
// → 5
// The `_.property` iteratee shorthand.
_.meanBy(objects, 'n');
// → 5
_.min(array)
Computes the minimum value of array
. If array
is empty or falsey,
undefined
is returned.
0.1.0
array
(Array): The array to iterate over.(*): Returns the minimum value.
_.min([4, 2, 8, 6]);
// → 2
_.min([]);
// → undefined
_.minBy(array, [iteratee=_.identity])
This method is like _.min
except that it accepts iteratee
which is
invoked for each element in array
to generate the criterion by which
the value is ranked. The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The array to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(*): Returns the minimum value.
var objects = [{ 'n': 1 }, { 'n': 2 }];
_.minBy(objects, function(o) { return o.n; });
// → { 'n': 1 }
// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// → { 'n': 1 }
_.multiply(multiplier, multiplicand)
Multiply two numbers.
4.7.0
multiplier
(number): The first number in a multiplication.multiplicand
(number): The second number in a multiplication.(number): Returns the product.
_.multiply(6, 4);
// → 24
_.round(number, [precision=0])
Computes number
rounded to precision
.
3.10.0
number
(number): The number to round.[precision=0]
(number): The precision to round to.(number): Returns the rounded number.
_.round(4.006);
// → 4
_.round(4.006, 2);
// → 4.01
_.round(4060, -2);
// → 4100
_.subtract(minuend, subtrahend)
Subtract two numbers.
4.0.0
minuend
(number): The first number in a subtraction.subtrahend
(number): The second number in a subtraction.(number): Returns the difference.
_.subtract(6, 4);
// → 2
_.sum(array)
Computes the sum of the values in array
.
3.4.0
array
(Array): The array to iterate over.(number): Returns the sum.
_.sum([4, 2, 8, 6]);
// → 20
_.sumBy(array, [iteratee=_.identity])
This method is like _.sum
except that it accepts iteratee
which is
invoked for each element in array
to generate the value to be summed.
The iteratee is invoked with one argument: (value).
4.0.0
array
(Array): The array to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(number): Returns the sum.
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];
_.sumBy(objects, function(o) { return o.n; });
// → 20
// The `_.property` iteratee shorthand.
_.sumBy(objects, 'n');
// → 20
“Number” Methods
_.clamp(number, [lower], upper)
Clamps number
within the inclusive lower
and upper
bounds.
4.0.0
number
(number): The number to clamp.[lower]
(number): The lower bound.upper
(number): The upper bound.(number): Returns the clamped number.
_.clamp(-10, -5, 5);
// → -5
_.clamp(10, -5, 5);
// → 5
_.inRange(number, [start=0], end)
Checks if n
is between start
and up to, but not including, end
. If
end
is not specified, it’s set to start
with start
then set to 0
.
If start
is greater than end
the params are swapped to support
negative ranges.
3.3.0
number
(number): The number to check.[start=0]
(number): The start of the range.end
(number): The end of the range.(boolean): Returns true
if number
is in the range, else false
.
_.inRange(3, 2, 4);
// → true
_.inRange(4, 8);
// → true
_.inRange(4, 2);
// → false
_.inRange(2, 2);
// → false
_.inRange(1.2, 2);
// → true
_.inRange(5.2, 4);
// → false
_.inRange(-3, -2, -6);
// → true
_.random([lower=0], [upper=1], [floating])
Produces a random number between the inclusive lower
and upper
bounds.
If only one argument is provided a number between 0
and the given number
is returned. If floating
is true
, or either lower
or upper
are
floats, a floating-point number is returned instead of an integer.
Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.
0.7.0
[lower=0]
(number): The lower bound.[upper=1]
(number): The upper bound.[floating]
(boolean): Specify returning a floating-point number.(number): Returns the random number.
_.random(0, 5);
// → an integer between 0 and 5
_.random(5);
// → also an integer between 0 and 5
_.random(5, true);
// → a floating-point number between 0 and 5
_.random(1.2, 5.2);
// → a floating-point number between 1.2 and 5.2
“Object” Methods
_.assign(object, [sources])
Assigns own enumerable string keyed properties of source objects to the
destination object. Source objects are applied from left to right.
Subsequent sources overwrite property assignments of previous sources.
Note: This method mutates object
and is loosely based on
Object.assign
.
0.10.0
object
(Object): The destination object.[sources]
(…Object): The source objects.(Object): Returns object
.
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
_.assign({ 'a': 1 }, new Foo, new Bar);
// → { 'a': 1, 'c': 3, 'e': 5 }
_.assignIn(object, [sources])
This method is like _.assign
except that it iterates over own and
inherited source properties.
Note: This method mutates object
.
4.0.0
_.extend
object
(Object): The destination object.[sources]
(…Object): The source objects.(Object): Returns object
.
function Foo() {
this.b = 2;
}
function Bar() {
this.d = 4;
}
Foo.prototype.c = 3;
Bar.prototype.e = 5;
_.assignIn({ 'a': 1 }, new Foo, new Bar);
// → { 'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5 }
_.assignInWith(object, sources, [customizer])
This method is like _.assignIn
except that it accepts customizer
which is invoked to produce the assigned values. If customizer
returns
undefined
, assignment is handled by the method instead. The customizer
is invoked with five arguments: (objValue, srcValue, key, object, source).
Note: This method mutates object
.
4.0.0
_.extendWith
object
(Object): The destination object.sources
(…Object): The source objects.[customizer]
(Function): The function to customize assigned values.(Object): Returns object
.
function customizer(objValue, srcValue) {
return _.isUndefined(objValue) ? srcValue : objValue;
}
var defaults = _.partialRight(_.assignInWith, customizer);
defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// → { 'a': 1, 'b': 2 }
_.assignWith(object, sources, [customizer])
This method is like _.assign
except that it accepts customizer
which is invoked to produce the assigned values. If customizer
returns
undefined
, assignment is handled by the method instead. The customizer
is invoked with five arguments: (objValue, srcValue, key, object, source).
Note: This method mutates object
.
4.0.0
object
(Object): The destination object.sources
(…Object): The source objects.[customizer]
(Function): The function to customize assigned values.(Object): Returns object
.
function customizer(objValue, srcValue) {
return _.isUndefined(objValue) ? srcValue : objValue;
}
var defaults = _.partialRight(_.assignWith, customizer);
defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// → { 'a': 1, 'b': 2 }
_.at(object, [paths])
Creates an array of values corresponding to paths
of object
.
1.0.0
object
(Object): The object to iterate over.[paths]
(…(string|string[])): The property paths of elements to pick.(Array): Returns the new array of picked elements.
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
_.at(object, ['a[0].b.c', 'a[1]']);
// → [3, 4]
_.at(['a', 'b', 'c'], 0, 2);
// → ['a', 'c']
_.create(prototype, [properties])
Creates an object that inherits from the prototype
object. If a
properties
object is given, its own enumerable string keyed properties
are assigned to the created object.
2.3.0
prototype
(Object): The object to inherit from.[properties]
(Object): The properties to assign to the object.(Object): Returns the new object.
function Shape() {
this.x = 0;
this.y = 0;
}
function Circle() {
Shape.call(this);
}
Circle.prototype = _.create(Shape.prototype, {
'constructor': Circle
});
var circle = new Circle;
circle instanceof Circle;
// → true
circle instanceof Shape;
// → true
_.defaults(object, [sources])
Assigns own and inherited enumerable string keyed properties of source
objects to the destination object for all destination properties that
resolve to undefined
. Source objects are applied from left to right.
Once a property is set, additional values of the same property are ignored.
Note: This method mutates object
.
0.1.0
object
(Object): The destination object.[sources]
(…Object): The source objects.(Object): Returns object
.
_.defaults({ 'user': 'barney' }, { 'age': 36 }, { 'user': 'fred' });
// → { 'user': 'barney', 'age': 36 }
_.defaultsDeep(object, [sources])
This method is like _.defaults
except that it recursively assigns
default properties.
Note: This method mutates object
.
3.10.0
object
(Object): The destination object.[sources]
(…Object): The source objects.(Object): Returns object
.
_.defaultsDeep({ 'user': { 'name': 'barney' } }, { 'user': { 'name': 'fred', 'age': 36 } });
// → { 'user': { 'name': 'barney', 'age': 36 } }
_.findKey(object, [predicate=_.identity])
This method is like _.find
except that it returns the key of the first
element predicate
returns truthy for instead of the element itself.
1.1.0
object
(Object): The object to search.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(*): Returns the key of the matched element, else undefined
.
var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findKey(users, function(o) { return o.age < 40; });
// → 'barney' (iteration order is not guaranteed)
// The `_.matches` iteratee shorthand.
_.findKey(users, { 'age': 1, 'active': true });
// → 'pebbles'
// The `_.matchesProperty` iteratee shorthand.
_.findKey(users, ['active', false]);
// → 'fred'
// The `_.property` iteratee shorthand.
_.findKey(users, 'active');
// → 'barney'
_.findLastKey(object, [predicate=_.identity])
This method is like _.findKey
except that it iterates over elements of
a collection in the opposite order.
2.0.0
object
(Object): The object to search.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(*): Returns the key of the matched element, else undefined
.
var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findLastKey(users, function(o) { return o.age < 40; });
// → returns 'pebbles' assuming `_.findKey` returns 'barney'
// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// → 'barney'
// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// → 'fred'
// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// → 'pebbles'
_.forIn(object, [iteratee=_.identity])
Iterates over own and inherited enumerable string keyed properties of an
object and invokes iteratee
for each property. The iteratee is invoked
with three arguments: (value, key, object). Iteratee functions may exit
iteration early by explicitly returning false
.
0.3.0
object
(Object): The object to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forIn(new Foo, function(value, key) {
console.log(key);
});
// → Logs 'a', 'b', then 'c' (iteration order is not guaranteed).
_.forInRight(object, [iteratee=_.identity])
This method is like _.forIn
except that it iterates over properties of
object
in the opposite order.
2.0.0
object
(Object): The object to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forInRight(new Foo, function(value, key) {
console.log(key);
});
// → Logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'.
_.forOwn(object, [iteratee=_.identity])
Iterates over own enumerable string keyed properties of an object and
invokes iteratee
for each property. The iteratee is invoked with three
arguments: (value, key, object). Iteratee functions may exit iteration
early by explicitly returning false
.
0.3.0
object
(Object): The object to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forOwn(new Foo, function(value, key) {
console.log(key);
});
// → Logs 'a' then 'b' (iteration order is not guaranteed).
_.forOwnRight(object, [iteratee=_.identity])
This method is like _.forOwn
except that it iterates over properties of
object
in the opposite order.
2.0.0
object
(Object): The object to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forOwnRight(new Foo, function(value, key) {
console.log(key);
});
// → Logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'.
_.functions(object)
Creates an array of function property names from own enumerable properties
of object
.
0.1.0
object
(Object): The object to inspect.(Array): Returns the new array of property names.
function Foo() {
this.a = _.constant('a');
this.b = _.constant('b');
}
Foo.prototype.c = _.constant('c');
_.functions(new Foo);
// → ['a', 'b']
_.functionsIn(object)
Creates an array of function property names from own and inherited
enumerable properties of object
.
4.0.0
object
(Object): The object to inspect.(Array): Returns the new array of property names.
function Foo() {
this.a = _.constant('a');
this.b = _.constant('b');
}
Foo.prototype.c = _.constant('c');
_.functionsIn(new Foo);
// → ['a', 'b', 'c']
_.get(object, path, [defaultValue])
Gets the value at path
of object
. If the resolved value is
undefined
, the defaultValue
is used in its place.
3.7.0
object
(Object): The object to query.path
(Array|string): The path of the property to get.[defaultValue]
(*): The value returned for undefined
resolved values.(*): Returns the resolved value.
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.get(object, 'a[0].b.c');
// → 3
_.get(object, ['a', '0', 'b', 'c']);
// → 3
_.get(object, 'a.b.c', 'default');
// → 'default'
_.has(object, path)
Checks if path
is a direct property of object
.
0.1.0
object
(Object): The object to query.path
(Array|string): The path to check.(boolean): Returns true
if path
exists, else false
.
var object = { 'a': { 'b': 2 } };
var other = _.create({ 'a': _.create({ 'b': 2 }) });
_.has(object, 'a');
// → true
_.has(object, 'a.b');
// → true
_.has(object, ['a', 'b']);
// → true
_.has(other, 'a');
// → false
_.hasIn(object, path)
Checks if path
is a direct or inherited property of object
.
4.0.0
object
(Object): The object to query.path
(Array|string): The path to check.(boolean): Returns true
if path
exists, else false
.
var object = _.create({ 'a': _.create({ 'b': 2 }) });
_.hasIn(object, 'a');
// → true
_.hasIn(object, 'a.b');
// → true
_.hasIn(object, ['a', 'b']);
// → true
_.hasIn(object, 'b');
// → false
_.invert(object)
Creates an object composed of the inverted keys and values of object
.
If object
contains duplicate values, subsequent values overwrite
property assignments of previous values.
0.7.0
object
(Object): The object to invert.(Object): Returns the new inverted object.
var object = { 'a': 1, 'b': 2, 'c': 1 };
_.invert(object);
// → { '1': 'c', '2': 'b' }
_.invertBy(object, [iteratee=_.identity])
This method is like _.invert
except that the inverted object is generated
from the results of running each element of object
thru iteratee
. The
corresponding inverted value of each inverted key is an array of keys
responsible for generating the inverted value. The iteratee is invoked
with one argument: (value).
4.1.0
object
(Object): The object to invert.[iteratee=_.identity]
(Array|Function|Object|string): The iteratee invoked per element.(Object): Returns the new inverted object.
var object = { 'a': 1, 'b': 2, 'c': 1 };
_.invertBy(object);
// → { '1': ['a', 'c'], '2': ['b'] }
_.invertBy(object, function(value) {
return 'group' + value;
});
// → { 'group1': ['a', 'c'], 'group2': ['b'] }
_.invoke(object, path, [args])
Invokes the method at path
of object
.
4.0.0
object
(Object): The object to query.path
(Array|string): The path of the method to invoke.[args]
(…*): The arguments to invoke the method with.(*): Returns the result of the invoked method.
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };
_.invoke(object, 'a[0].b.c.slice', 1, 3);
// → [2, 3]
_.keys(object)
Creates an array of the own enumerable property names of object
.
Note: Non-object values are coerced to objects. See the
ES spec
for more details.
0.1.0
object
(Object): The object to query.(Array): Returns the array of property names.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.keys(new Foo);
// → ['a', 'b'] (iteration order is not guaranteed)
_.keys('hi');
// → ['0', '1']
_.keysIn(object)
Creates an array of the own and inherited enumerable property names of object
.
Note: Non-object values are coerced to objects.
3.0.0
object
(Object): The object to query.(Array): Returns the array of property names.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.keysIn(new Foo);
// → ['a', 'b', 'c'] (iteration order is not guaranteed)
_.mapKeys(object, [iteratee=_.identity])
The opposite of _.mapValues
; this method creates an object with the
same values as object
and keys generated by running each own enumerable
string keyed property of object
thru iteratee
. The iteratee is invoked
with three arguments: (value, key, object).
3.8.0
object
(Object): The object to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Object): Returns the new mapped object.
_.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
return key + value;
});
// → { 'a1': 1, 'b2': 2 }
_.mapValues(object, [iteratee=_.identity])
Creates an object with the same keys as object
and values generated
by running each own enumerable string keyed property of object
thru
iteratee
. The iteratee is invoked with three arguments:
(value, key, object).
2.4.0
object
(Object): The object to iterate over.[iteratee=_.identity]
(Array|Function|Object|string): The function invoked per iteration.(Object): Returns the new mapped object.
var users = {
'fred': { 'user': 'fred', 'age': 40 },
'pebbles': { 'user': 'pebbles', 'age': 1 }
};
_.mapValues(users, function(o) { return o.age; });
// → { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
// The `_.property` iteratee shorthand.
_.mapValues(users, 'age');
// → { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
_.merge(object, [sources])
This method is like _.assign
except that it recursively merges own and
inherited enumerable string keyed properties of source objects into the
destination object. Source properties that resolve to undefined
are
skipped if a destination value exists. Array and plain object properties
are merged recursively.Other objects and value types are overridden by
assignment. Source objects are applied from left to right. Subsequent
sources overwrite property assignments of previous sources.
Note: This method mutates object
.
0.5.0
object
(Object): The destination object.[sources]
(…Object): The source objects.(Object): Returns object
.
var users = {
'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
};
var ages = {
'data': [{ 'age': 36 }, { 'age': 40 }]
};
_.merge(users, ages);
// → { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }
_.mergeWith(object, sources, customizer)
This method is like _.merge
except that it accepts customizer
which
is invoked to produce the merged values of the destination and source
properties. If customizer
returns undefined
, merging is handled by the
method instead. The customizer
is invoked with seven arguments:
(objValue, srcValue, key, object, source, stack).
Note: This method mutates object
.
4.0.0
object
(Object): The destination object.sources
(…Object): The source objects.customizer
(Function): The function to customize assigned values.(Object): Returns object
.
function customizer(objValue, srcValue) {
if (_.isArray(objValue)) {
return objValue.concat(srcValue);
}
}
var object = {
'fruits': ['apple'],
'vegetables': ['beet']
};
var other = {
'fruits': ['banana'],
'vegetables': ['carrot']
};
_.mergeWith(object, other, customizer);
// → { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }
_.omit(object, [props])
The opposite of _.pick
; this method creates an object composed of the
own and inherited enumerable string keyed properties of object
that are
not omitted.
0.1.0
object
(Object): The source object.[props]
(…(string|string[])): The property identifiers to omit.(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.omit(object, ['a', 'c']);
// → { 'b': '2' }
_.omitBy(object, [predicate=_.identity])
The opposite of _.pickBy
; this method creates an object composed of
the own and inherited enumerable string keyed properties of object
that
predicate
doesn’t return truthy for. The predicate is invoked with two
arguments: (value, key).
4.0.0
object
(Object): The source object.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per property.(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.omitBy(object, _.isNumber);
// → { 'b': '2' }
_.pick(object, [props])
Creates an object composed of the picked object
properties.
0.1.0
object
(Object): The source object.[props]
(…(string|string[])): The property identifiers to pick.(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.pick(object, ['a', 'c']);
// → { 'a': 1, 'c': 3 }
_.pickBy(object, [predicate=_.identity])
Creates an object composed of the object
properties predicate
returns
truthy for. The predicate is invoked with two arguments: (value, key).
4.0.0
object
(Object): The source object.[predicate=_.identity]
(Array|Function|Object|string): The function invoked per property.(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.pickBy(object, _.isNumber);
// → { 'a': 1, 'c': 3 }
_.result(object, path, [defaultValue])
This method is like _.get
except that if the resolved value is a
function it’s invoked with the this
binding of its parent object and
its result is returned.
0.1.0
object
(Object): The object to query.path
(Array|string): The path of the property to resolve.[defaultValue]
(*): The value returned for undefined
resolved values.(*): Returns the resolved value.
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };
_.result(object, 'a[0].b.c1');
// → 3
_.result(object, 'a[0].b.c2');
// → 4
_.result(object, 'a[0].b.c3', 'default');
// → 'default'
_.result(object, 'a[0].b.c3', _.constant('default'));
// → 'default'
_.set(object, path, value)
Sets the value at path
of object
. If a portion of path
doesn’t exist,
it’s created. Arrays are created for missing index properties while objects
are created for all other missing properties. Use _.setWith
to customize
path
creation.
Note: This method mutates object
.
3.7.0
object
(Object): The object to modify.path
(Array|string): The path of the property to set.value
(*): The value to set.(Object): Returns object
.
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.set(object, 'a[0].b.c', 4);
console.log(object.a[0].b.c);
// → 4
_.set(object, ['x', '0', 'y', 'z'], 5);
console.log(object.x[0].y.z);
// → 5
_.setWith(object, path, value, [customizer])
This method is like _.set
except that it accepts customizer
which is
invoked to produce the objects of path
. If customizer
returns undefined
path creation is handled by the method instead. The customizer
is invoked
with three arguments: (nsValue, key, nsObject).
Note: This method mutates object
.
4.0.0
object
(Object): The object to modify.path
(Array|string): The path of the property to set.value
(*): The value to set.[customizer]
(Function): The function to customize assigned values.(Object): Returns object
.
var object = {};
_.setWith(object, '[0][1]', 'a', Object);
// → { '0': { '1': 'a' } }
_.toPairs(object)
Creates an array of own enumerable string keyed-value pairs for object
which can be consumed by _.fromPairs
.
4.0.0
_.entries
object
(Object): The object to query.(Array): Returns the new array of key-value pairs.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.toPairs(new Foo);
// → [['a', 1], ['b', 2]] (iteration order is not guaranteed)
_.toPairsIn(object)
Creates an array of own and inherited enumerable string keyed-value pairs
for object
which can be consumed by _.fromPairs
.
4.0.0
_.entriesIn
object
(Object): The object to query.(Array): Returns the new array of key-value pairs.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.toPairsIn(new Foo);
// → [['a', 1], ['b', 2], ['c', 1]] (iteration order is not guaranteed)
_.transform(object, [iteratee=_.identity], [accumulator])
An alternative to _.reduce
; this method transforms object
to a new
accumulator
object which is the result of running each of its own
enumerable string keyed properties thru iteratee
, with each invocation
potentially mutating the accumulator
object. The iteratee is invoked
with four arguments: (accumulator, value, key, object). Iteratee functions
may exit iteration early by explicitly returning false
.
1.3.0
object
(Array|Object): The object to iterate over.[iteratee=_.identity]
(Function): The function invoked per iteration.[accumulator]
(*): The custom accumulator value.(*): Returns the accumulated value.
_.transform([2, 3, 4], function(result, n) {
result.push(n *= n);
return n % 2 == 0;
}, []);
// → [4, 9]
_.transform({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
(result[value] || (result[value] = [])).push(key);
}, {});
// → { '1': ['a', 'c'], '2': ['b'] }
_.unset(object, path)
Removes the property at path
of object
.
Note: This method mutates object
.
4.0.0
object
(Object): The object to modify.path
(Array|string): The path of the property to unset.(boolean): Returns true
if the property is deleted, else false
.
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset(object, 'a[0].b.c');
// → true
console.log(object);
// → { 'a': [{ 'b': {} }] };
_.unset(object, ['a', '0', 'b', 'c']);
// → true
console.log(object);
// → { 'a': [{ 'b': {} }] };
_.update(object, path, updater)
This method is like _.set
except that accepts updater
to produce the
value to set. Use _.updateWith
to customize path
creation. The updater
is invoked with one argument: (value).
Note: This method mutates object
.
4.6.0
object
(Object): The object to modify.path
(Array|string): The path of the property to set.updater
(Function): The function to produce the updated value.(Object): Returns object
.
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.update(object, 'a[0].b.c', function(n) { return n * n; });
console.log(object.a[0].b.c);
// → 9
_.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
console.log(object.x[0].y.z);
// → 0
_.updateWith(object, path, updater, [customizer])
This method is like _.update
except that it accepts customizer
which is
invoked to produce the objects of path
. If customizer
returns undefined
path creation is handled by the method instead. The customizer
is invoked
with three arguments: (nsValue, key, nsObject).
Note: This method mutates object
.
4.6.0
object
(Object): The object to modify.path
(Array|string): The path of the property to set.updater
(Function): The function to produce the updated value.[customizer]
(Function): The function to customize assigned values.(Object): Returns object
.
var object = {};
_.updateWith(object, '[0][1]', _.constant('a'), Object);
// → { '0': { '1': 'a' } }
_.values(object)
Creates an array of the own enumerable string keyed property values of object
.
Note: Non-object values are coerced to objects.
0.1.0
object
(Object): The object to query.(Array): Returns the array of property values.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.values(new Foo);
// → [1, 2] (iteration order is not guaranteed)
_.values('hi');
// → ['h', 'i']
_.valuesIn(object)
Creates an array of the own and inherited enumerable string keyed property
values of object
.
Note: Non-object values are coerced to objects.
3.0.0
object
(Object): The object to query.(Array): Returns the array of property values.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.valuesIn(new Foo);
// → [1, 2, 3] (iteration order is not guaranteed)
“Seq” Methods
_(value)
Creates a lodash
object which wraps value
to enable implicit method
chain sequences. Methods that operate on and return arrays, collections,
and functions can be chained together. Methods that retrieve a single value
or may return a primitive value will automatically end the chain sequence
and return the unwrapped value. Otherwise, the value must be unwrapped
with _#value
.
Explicit chain sequences, which must be unwrapped with _#value
, may be
enabled using _.chain
.
The execution of chained methods is lazy, that is, it’s deferred until
_#value
is implicitly or explicitly called.
Lazy evaluation allows several methods to support shortcut fusion.
Shortcut fusion is an optimization to merge iteratee calls; this avoids
the creation of intermediate arrays and can greatly reduce the number of
iteratee executions. Sections of a chain sequence qualify for shortcut
fusion if the section is applied to an array of at least 200
elements
and any iteratees accept only one argument. The heuristic for whether a
section qualifies for shortcut fusion is subject to change.
Chaining is supported in custom builds as long as the _#value
method is
directly or indirectly included in the build.
In addition to lodash methods, wrappers have Array
and String
methods.
The wrapper Array
methods are:
concat
, join
, pop
, push
, shift
, sort
, splice
, and unshift
The wrapper String
methods are:
replace
and split
The wrapper methods that support shortcut fusion are:
at
, compact
, drop
, dropRight
, dropWhile
, filter
, find
,
findLast
, head
, initial
, last
, map
, reject
, reverse
, slice
,
tail
, take
, takeRight
, takeRightWhile
, takeWhile
, and toArray
The chainable wrapper methods are:
after
, ary
, assign
, assignIn
, assignInWith
, assignWith
, at
,
before
, bind
, bindAll
, bindKey
, castArray
, chain
, chunk
,
commit
, compact
, concat
, conforms
, constant
, countBy
, create
,
curry
, debounce
, defaults
, defaultsDeep
, defer
, delay
,
difference
, differenceBy
, differenceWith
, drop
, dropRight
,
dropRightWhile
, dropWhile
, extend
, extendWith
, fill
, filter
,
flatMap
, flatMapDeep
, flatMapDepth
, flatten
, flattenDeep
,
flattenDepth
, flip
, flow
, flowRight
, fromPairs
, functions
,
functionsIn
, groupBy
, initial
, intersection
, intersectionBy
,
intersectionWith
, invert
, invertBy
, invokeMap
, iteratee
, keyBy
,
keys
, keysIn
, map
, mapKeys
, mapValues
, matches
, matchesProperty
,
memoize
, merge
, mergeWith
, method
, methodOf
, mixin
, negate
,
nthArg
, omit
, omitBy
, once
, orderBy
, over
, overArgs
,
overEvery
, overSome
, partial
, partialRight
, partition
, pick
,
pickBy
, plant
, property
, propertyOf
, pull
, pullAll
, pullAllBy
,
pullAllWith
, pullAt
, push
, range
, rangeRight
, rearg
, reject
,
remove
, rest
, reverse
, sampleSize
, set
, setWith
, shuffle
,
slice
, sort
, sortBy
, splice
, spread
, tail
, take
, takeRight
,
takeRightWhile
, takeWhile
, tap
, throttle
, thru
, toArray
,
toPairs
, toPairsIn
, toPath
, toPlainObject
, transform
, unary
,
union
, unionBy
, unionWith
, uniq
, uniqBy
, uniqWith
, unset
,
unshift
, unzip
, unzipWith
, update
, updateWith
, values
,
valuesIn
, without
, wrap
, xor
, xorBy
, xorWith
, zip
,
zipObject
, zipObjectDeep
, and zipWith
The wrapper methods that are not chainable by default are:
add
, attempt
, camelCase
, capitalize
, ceil
, clamp
, clone
,
cloneDeep
, cloneDeepWith
, cloneWith
, deburr
, divide
, each
,
eachRight
, endsWith
, eq
, escape
, escapeRegExp
, every
, find
,
findIndex
, findKey
, findLast
, findLastIndex
, findLastKey
, first
,
floor
, forEach
, forEachRight
, forIn
, forInRight
, forOwn
,
forOwnRight
, get
, gt
, gte
, has
, hasIn
, head
, identity
,
includes
, indexOf
, inRange
, invoke
, isArguments
, isArray
,
isArrayBuffer
, isArrayLike
, isArrayLikeObject
, isBoolean
, isBuffer
,
isDate
, isElement
, isEmpty
, isEqual
, isEqualWith
, isError
,
isFinite
, isFunction
, isInteger
, isLength
, isMap
, isMatch
,
isMatchWith
, isNaN
, isNative
, isNil
, isNull
, isNumber
,
isObject
, isObjectLike
, isPlainObject
, isRegExp
, isSafeInteger
,
isSet
, isString
, isUndefined
, isTypedArray
, isWeakMap
, isWeakSet
,
join
, kebabCase
, last
, lastIndexOf
, lowerCase
, lowerFirst
,
lt
, lte
, max
, maxBy
, mean
, meanBy
, min
, minBy
, multiply
,
noConflict
, noop
, now
, nth
, pad
, padEnd
, padStart
, parseInt
,
pop
, random
, reduce
, reduceRight
, repeat
, result
, round
,
runInContext
, sample
, shift
, size
, snakeCase
, some
, sortedIndex
,
sortedIndexBy
, sortedLastIndex
, sortedLastIndexBy
, startCase
,
startsWith
, subtract
, sum
, sumBy
, template
, times
, toInteger
,
toJSON
, toLength
, toLower
, toNumber
, toSafeInteger
, toString
,
toUpper
, trim
, trimEnd
, trimStart
, truncate
, unescape
,
uniqueId
, upperCase
, upperFirst
, value
, and words
value
(*): The value to wrap in a lodash
instance.(Object): Returns the new lodash
wrapper instance.
function square(n) {
return n * n;
}
var wrapped = _([1, 2, 3]);
// Returns an unwrapped value.
wrapped.reduce(_.add);
// → 6
// Returns a wrapped value.
var squares = wrapped.map(square);
_.isArray(squares);
// → false
_.isArray(squares.value());
// → true
_.chain(value)
Creates a lodash
wrapper instance that wraps value
with explicit method
chain sequences enabled. The result of such sequences must be unwrapped
with _#value
.
1.3.0
value
(*): The value to wrap.(Object): Returns the new lodash
wrapper instance.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 },
{ 'user': 'pebbles', 'age': 1 }
];
var youngest = _
.chain(users)
.sortBy('age')
.map(function(o) {
return o.user + ' is ' + o.age;
})
.head()
.value();
// → 'pebbles is 1'
_.tap(value, interceptor)
This method invokes interceptor
and returns value
. The interceptor
is invoked with one argument; (value). The purpose of this method is to
"tap into" a method chain sequence in order to modify intermediate results.
0.1.0
value
(*): The value to provide to interceptor
.interceptor
(Function): The function to invoke.(*): Returns value
.
_([1, 2, 3])
.tap(function(array) {
// Mutate input array.
array.pop();
})
.reverse()
.value();
// → [2, 1]
_.thru(value, interceptor)
This method is like _.tap
except that it returns the result of interceptor
.
The purpose of this method is to "pass thru" values replacing intermediate
results in a method chain sequence.
3.0.0
value
(*): The value to provide to interceptor
.interceptor
(Function): The function to invoke.(*): Returns the result of interceptor
.
_(' abc ')
.chain()
.trim()
.thru(function(value) {
return [value];
})
.value();
// → ['abc']
_.prototype[Symbol.iterator]()
Enables the wrapper to be iterable.
4.0.0
(Object): Returns the wrapper object.
var wrapped = _([1, 2]);
wrapped[Symbol.iterator]() === wrapped;
// → true
Array.from(wrapped);
// → [1, 2]
_.prototype.at([paths])
This method is the wrapper version of _.at
.
1.0.0
[paths]
(…(string|string[])): The property paths of elements to pick.(Object): Returns the new lodash
wrapper instance.
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
_(object).at(['a[0].b.c', 'a[1]']).value();
// → [3, 4]
_(['a', 'b', 'c']).at(0, 2).value();
// → ['a', 'c']
_.prototype.chain()
Creates a lodash
wrapper instance with explicit method chain sequences enabled.
0.1.0
(Object): Returns the new lodash
wrapper instance.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
// A sequence without explicit chaining.
_(users).head();
// → { 'user': 'barney', 'age': 36 }
// A sequence with explicit chaining.
_(users)
.chain()
.head()
.pick('user')
.value();
// → { 'user': 'barney' }
_.prototype.commit()
Executes the chain sequence and returns the wrapped result.
3.2.0
(Object): Returns the new lodash
wrapper instance.
var array = [1, 2];
var wrapped = _(array).push(3);
console.log(array);
// → [1, 2]
wrapped = wrapped.commit();
console.log(array);
// → [1, 2, 3]
wrapped.last();
// → 3
console.log(array);
// → [1, 2, 3]
_.prototype.next()
Gets the next value on a wrapped object following the iterator protocol.
4.0.0
(Object): Returns the next iterator value.
var wrapped = _([1, 2]);
wrapped.next();
// → { 'done': false, 'value': 1 }
wrapped.next();
// → { 'done': false, 'value': 2 }
wrapped.next();
// → { 'done': true, 'value': undefined }
_.prototype.plant(value)
Creates a clone of the chain sequence planting value
as the wrapped value.
3.2.0
value
(*): The value to plant.(Object): Returns the new lodash
wrapper instance.
function square(n) {
return n * n;
}
var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);
other.value();
// → [9, 16]
wrapped.value();
// → [1, 4]
_.prototype.reverse()
This method is the wrapper version of _.reverse
.
Note: This method mutates the wrapped array.
0.1.0
(Object): Returns the new lodash
wrapper instance.
var array = [1, 2, 3];
_(array).reverse().value()
// → [3, 2, 1]
console.log(array);
// → [3, 2, 1]
“String” Methods
_.camelCase([string=''])
Converts string
to camel case.
3.0.0
[string='']
(string): The string to convert.(string): Returns the camel cased string.
_.camelCase('Foo Bar');
// → 'fooBar'
_.camelCase('--foo-bar--');
// → 'fooBar'
_.camelCase('__FOO_BAR__');
// → 'fooBar'
_.capitalize([string=''])
Converts the first character of string
to upper case and the remaining
to lower case.
3.0.0
[string='']
(string): The string to capitalize.(string): Returns the capitalized string.
_.capitalize('FRED');
// → 'Fred'
_.deburr([string=''])
Deburrs string
by converting
latin-1 supplementary letters
to basic latin letters and removing
combining diacritical marks.
3.0.0
[string='']
(string): The string to deburr.(string): Returns the deburred string.
_.deburr('déjà vu');
// → 'deja vu'
_.endsWith([string=''], [target], [position=string.length])
Checks if string
ends with the given target string.
3.0.0
[string='']
(string): The string to search.[target]
(string): The string to search for.[position=string.length]
(number): The position to search from.(boolean): Returns true
if string
ends with target
, else false
.
_.endsWith('abc', 'c');
// → true
_.endsWith('abc', 'b');
// → false
_.endsWith('abc', 'b', 2);
// → true
_.escape([string=''])
Converts the characters "&", "<", ">", '"', "'", and "`" in string
to
their corresponding HTML entities.
Note: No other characters are escaped. To escape additional
characters use a third-party library like he.
Though the ">" character is escaped for symmetry, characters like
">" and "/" don’t need escaping in HTML and have no special meaning
unless they're part of a tag or unquoted attribute value. See
Mathias Bynens’s article
(under "semi-related fun fact") for more details.
Backticks are escaped because in IE < 9
, they can break out of
attribute values or HTML comments. See #59,
#102, #108, and
#133 of the
HTML5 Security Cheatsheet for more details.
When working with HTML you should always
quote attribute values to reduce
XSS vectors.
0.1.0
[string='']
(string): The string to escape.(string): Returns the escaped string.
_.escape('fred, barney, & pebbles');
// → 'fred, barney, & pebbles'
_.escapeRegExp([string=''])
Escapes the RegExp
special characters "^", "$", "\", ".", "*", "+",
"?", "(", ")", "[", "]", "{", "}", and "|" in string
.
3.0.0
[string='']
(string): The string to escape.(string): Returns the escaped string.
_.escapeRegExp('[lodash](https://lodash.com/)');
// → '\[lodash\]\(https://lodash\.com/\)'
_.kebabCase([string=''])
Converts string
to
kebab case.
3.0.0
[string='']
(string): The string to convert.(string): Returns the kebab cased string.
_.kebabCase('Foo Bar');
// → 'foo-bar'
_.kebabCase('fooBar');
// → 'foo-bar'
_.kebabCase('__FOO_BAR__');
// → 'foo-bar'
_.lowerCase([string=''])
Converts string
, as space separated words, to lower case.
4.0.0
[string='']
(string): The string to convert.(string): Returns the lower cased string.
_.lowerCase('--Foo-Bar--');
// → 'foo bar'
_.lowerCase('fooBar');
// → 'foo bar'
_.lowerCase('__FOO_BAR__');
// → 'foo bar'
_.lowerFirst([string=''])
Converts the first character of string
to lower case.
4.0.0
[string='']
(string): The string to convert.(string): Returns the converted string.
_.lowerFirst('Fred');
// → 'fred'
_.lowerFirst('FRED');
// → 'fRED'
_.pad([string=''], [length=0], [chars=' '])
Pads string
on the left and right sides if it’s shorter than length
.
Padding characters are truncated if they can’t be evenly divided by length
.
3.0.0
[string='']
(string): The string to pad.[length=0]
(number): The padding length.[chars=' ']
(string): The string used as padding.(string): Returns the padded string.
_.pad('abc', 8);
// → ' abc '
_.pad('abc', 8, '_-');
// → '_-abc_-_'
_.pad('abc', 3);
// → 'abc'
_.padEnd([string=''], [length=0], [chars=' '])
Pads string
on the right side if it’s shorter than length
. Padding
characters are truncated if they exceed length
.
4.0.0
[string='']
(string): The string to pad.[length=0]
(number): The padding length.[chars=' ']
(string): The string used as padding.(string): Returns the padded string.
_.padEnd('abc', 6);
// → 'abc '
_.padEnd('abc', 6, '_-');
// → 'abc_-_'
_.padEnd('abc', 3);
// → 'abc'
_.padStart([string=''], [length=0], [chars=' '])
Pads string
on the left side if it’s shorter than length
. Padding
characters are truncated if they exceed length
.
4.0.0
[string='']
(string): The string to pad.[length=0]
(number): The padding length.[chars=' ']
(string): The string used as padding.(string): Returns the padded string.
_.padStart('abc', 6);
// → ' abc'
_.padStart('abc', 6, '_-');
// → '_-_abc'
_.padStart('abc', 3);
// → 'abc'
_.parseInt(string, [radix=10])
Converts string
to an integer of the specified radix. If radix
is
undefined
or 0
, a radix
of 10
is used unless value
is a
hexadecimal, in which case a radix
of 16
is used.
Note: This method aligns with the
ES5 implementation of parseInt
.
1.1.0
string
(string): The string to convert.[radix=10]
(number): The radix to interpret value
by.(number): Returns the converted integer.
_.parseInt('08');
// → 8
_.map(['6', '08', '10'], _.parseInt);
// → [6, 8, 10]
_.repeat([string=''], [n=1])
Repeats the given string n
times.
3.0.0
[string='']
(string): The string to repeat.[n=1]
(number): The number of times to repeat the string.(string): Returns the repeated string.
_.repeat('*', 3);
// → '***'
_.repeat('abc', 2);
// → 'abcabc'
_.repeat('abc', 0);
// → ''
_.replace([string=''], pattern, replacement)
Replaces matches for pattern
in string
with replacement
.
Note: This method is based on
String#replace
.
4.0.0
[string='']
(string): The string to modify.pattern
(RegExp|string): The pattern to replace.replacement
(Function|string): The match replacement.(string): Returns the modified string.
_.replace('Hi Fred', 'Fred', 'Barney');
// → 'Hi Barney'
_.snakeCase([string=''])
Converts string
to
snake case.
3.0.0
[string='']
(string): The string to convert.(string): Returns the snake cased string.
_.snakeCase('Foo Bar');
// → 'foo_bar'
_.snakeCase('fooBar');
// → 'foo_bar'
_.snakeCase('--FOO-BAR--');
// → 'foo_bar'
_.split([string=''], separator, [limit])
Splits string
by separator
.
Note: This method is based on
String#split
.
4.0.0
[string='']
(string): The string to split.separator
(RegExp|string): The separator pattern to split by.[limit]
(number): The length to truncate results to.(Array): Returns the new array of string segments.
_.split('a-b-c', '-', 2);
// → ['a', 'b']
_.startCase([string=''])
Converts string
to
start case.
3.1.0
[string='']
(string): The string to convert.(string): Returns the start cased string.
_.startCase('--foo-bar--');
// → 'Foo Bar'
_.startCase('fooBar');
// → 'Foo Bar'
_.startCase('__FOO_BAR__');
// → 'FOO BAR'
_.startsWith([string=''], [target], [position=0])
Checks if string
starts with the given target string.
3.0.0
[string='']
(string): The string to search.[target]
(string): The string to search for.[position=0]
(number): The position to search from.(boolean): Returns true
if string
starts with target
, else false
.
_.startsWith('abc', 'a');
// → true
_.startsWith('abc', 'b');
// → false
_.startsWith('abc', 'b', 1);
// → true
_.template([string=''], [options={}], [options.escape=_.templateSettings.escape], [options.evaluate=_.templateSettings.evaluate], [options.imports=_.templateSettings.imports], [options.interpolate=_.templateSettings.interpolate], [options.sourceURL='lodash.templateSources[n]'], [options.variable='obj'])
Creates a compiled template function that can interpolate data properties
in "interpolate" delimiters, HTML-escape interpolated data properties in
"escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data
properties may be accessed as free variables in the template. If a setting
object is given, it takes precedence over _.templateSettings
values.
Note: In the development build _.template
utilizes
sourceURLs
for easier debugging.
For more information on precompiling templates see
lodash’s custom builds documentation.
For more information on Chrome extension sandboxes see
Chrome’s extensions documentation.
0.1.0
[string='']
(string): The template string.[options={}]
(Object): The options object.[options.escape=_.templateSettings.escape]
(RegExp): The HTML "escape" delimiter.[options.evaluate=_.templateSettings.evaluate]
(RegExp): The "evaluate" delimiter.[options.imports=_.templateSettings.imports]
(Object): An object to import into the template as free variables.[options.interpolate=_.templateSettings.interpolate]
(RegExp): The "interpolate" delimiter.[options.sourceURL='lodash.templateSources[n]']
(string): The sourceURL of the compiled template.[options.variable='obj']
(string): The data object variable name.(Function): Returns the compiled template function.
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// → 'hello fred!'
// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// → '<b><script></b>'
// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// → '<li>fred</li><li>barney</li>'
// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// → 'hello barney!'
// Use the ES delimiter as an alternative to the default "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// → 'hello pebbles!'
// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// → 'hello mustache!'
// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// → '<%- value %>'
// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template(text, { 'imports': { 'jq': jQuery } });
compiled({ 'users': ['fred', 'barney'] });
// → '<li>fred</li><li>barney</li>'
// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template('hello <%= user %>!', { 'sourceURL': '/basic/greeting.jst' });
compiled(data);
// → Find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector.
// Use the `variable` option to ensure a with-statement isn’t used in the compiled template.
var compiled = _.template('hi <%= data.user %>!', { 'variable': 'data' });
compiled.source;
// → function(data) {
// var __t, __p = '';
// __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
// return __p;
// }
// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(cwd, 'jst.js'), '\
var JST = {\
"main": ' + _.template(mainText).source + '\
};\
');
_.toLower([string=''])
Converts string
, as a whole, to lower case just like
String#toLowerCase.
4.0.0
[string='']
(string): The string to convert.(string): Returns the lower cased string.
_.toLower('--Foo-Bar--');
// → '--foo-bar--'
_.toLower('fooBar');
// → 'foobar'
_.toLower('__FOO_BAR__');
// → '__foo_bar__'
_.toUpper([string=''])
Converts string
, as a whole, to upper case just like
String#toUpperCase.
4.0.0
[string='']
(string): The string to convert.(string): Returns the upper cased string.
_.toUpper('--foo-bar--');
// → '--FOO-BAR--'
_.toUpper('fooBar');
// → 'FOOBAR'
_.toUpper('__foo_bar__');
// → '__FOO_BAR__'
_.trim([string=''], [chars=whitespace])
Removes leading and trailing whitespace or specified characters from string
.
3.0.0
[string='']
(string): The string to trim.[chars=whitespace]
(string): The characters to trim.(string): Returns the trimmed string.
_.trim(' abc ');
// → 'abc'
_.trim('-_-abc-_-', '_-');
// → 'abc'
_.map([' foo ', ' bar '], _.trim);
// → ['foo', 'bar']
_.trimEnd([string=''], [chars=whitespace])
Removes trailing whitespace or specified characters from string
.
4.0.0
[string='']
(string): The string to trim.[chars=whitespace]
(string): The characters to trim.(string): Returns the trimmed string.
_.trimEnd(' abc ');
// → ' abc'
_.trimEnd('-_-abc-_-', '_-');
// → '-_-abc'
_.trimStart([string=''], [chars=whitespace])
Removes leading whitespace or specified characters from string
.
4.0.0
[string='']
(string): The string to trim.[chars=whitespace]
(string): The characters to trim.(string): Returns the trimmed string.
_.trimStart(' abc ');
// → 'abc '
_.trimStart('-_-abc-_-', '_-');
// → 'abc-_-'
_.truncate([string=''], [options={}], [options.length=30], [options.omission='…'], [options.separator])
Truncates string
if it’s longer than the given maximum string length.
The last characters of the truncated string are replaced with the omission
string which defaults to "…".
4.0.0
[string='']
(string): The string to truncate.[options={}]
(Object): The options object.[options.length=30]
(number): The maximum string length.[options.omission='…']
(string): The string to indicate text is omitted.[options.separator]
(RegExp|string): The separator pattern to truncate to.(string): Returns the truncated string.
_.truncate('hi-diddly-ho there, neighborino');
// → 'hi-diddly-ho there, neighbo…'
_.truncate('hi-diddly-ho there, neighborino', {
'length': 24,
'separator': ' '
});
// → 'hi-diddly-ho there,…'
_.truncate('hi-diddly-ho there, neighborino', {
'length': 24,
'separator': /,? +/
});
// → 'hi-diddly-ho there…'
_.truncate('hi-diddly-ho there, neighborino', {
'omission': ' […]'
});
// → 'hi-diddly-ho there, neig […]'
_.unescape([string=''])
The inverse of _.escape
; this method converts the HTML entities
&
, <
, >
, "
, '
, and `
in string
to
their corresponding characters.
Note: No other HTML entities are unescaped. To unescape additional
HTML entities use a third-party library like he.
0.6.0
[string='']
(string): The string to unescape.(string): Returns the unescaped string.
_.unescape('fred, barney, & pebbles');
// → 'fred, barney, & pebbles'
_.upperCase([string=''])
Converts string
, as space separated words, to upper case.
4.0.0
[string='']
(string): The string to convert.(string): Returns the upper cased string.
_.upperCase('--foo-bar');
// → 'FOO BAR'
_.upperCase('fooBar');
// → 'FOO BAR'
_.upperCase('__foo_bar__');
// → 'FOO BAR'
_.upperFirst([string=''])
Converts the first character of string
to upper case.
4.0.0
[string='']
(string): The string to convert.(string): Returns the converted string.
_.upperFirst('fred');
// → 'Fred'
_.upperFirst('FRED');
// → 'FRED'
_.words([string=''], [pattern])
Splits string
into an array of its words.
3.0.0
[string='']
(string): The string to inspect.[pattern]
(RegExp|string): The pattern to match words.(Array): Returns the words of string
.
_.words('fred, barney, & pebbles');
// → ['fred', 'barney', 'pebbles']
_.words('fred, barney, & pebbles', /[^, ]+/g);
// → ['fred', 'barney', '&', 'pebbles']
“Util” Methods
_.attempt(func, [args])
Attempts to invoke func
, returning either the result or the caught error
object. Any additional arguments are provided to func
when it’s invoked.
3.0.0
func
(Function): The function to attempt.[args]
(…*): The arguments to invoke func
with.(*): Returns the func
result or error object.
// Avoid throwing errors for invalid selectors.
var elements = _.attempt(function(selector) {
return document.querySelectorAll(selector);
}, '>_>');
if (_.isError(elements)) {
elements = [];
}
_.bindAll(object, methodNames)
Binds methods of an object to the object itself, overwriting the existing
method.
Note: This method doesn’t set the "length" property of bound functions.
0.1.0
object
(Object): The object to bind and assign the bound methods to.methodNames
(…(string|string[])): The object method names to bind.(Object): Returns object
.
var view = {
'label': 'docs',
'onClick': function() {
console.log('clicked ' + this.label);
}
};
_.bindAll(view, 'onClick');
jQuery(element).on('click', view.onClick);
// → Logs 'clicked docs' when clicked.
_.cond(pairs)
Creates a function that iterates over pairs
and invokes the corresponding
function of the first predicate to return truthy. The predicate-function
pairs are invoked with the this
binding and arguments of the created
function.
4.0.0
pairs
(Array): The predicate-function pairs.(Function): Returns the new function.
var func = _.cond([
[_.matches({ 'a': 1 }), _.constant('matches A')],
[_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
[_.constant(true), _.constant('no match')]
]);
func({ 'a': 1, 'b': 2 });
// → 'matches A'
func({ 'a': 0, 'b': 1 });
// → 'matches B'
func({ 'a': '1', 'b': '2' });
// → 'no match'
_.conforms(source)
Creates a function that invokes the predicate properties of source
with
the corresponding property values of a given object, returning true
if
all predicates return truthy, else false
.
4.0.0
source
(Object): The object of property predicates to conform to.(Function): Returns the new function.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
_.filter(users, _.conforms({ 'age': _.partial(_.gt, _, 38) }));
// → [{ 'user': 'fred', 'age': 40 }]
_.constant(value)
Creates a function that returns value
.
2.4.0
value
(*): The value to return from the new function.(Function): Returns the new function.
var object = { 'user': 'fred' };
var getter = _.constant(object);
getter() === object;
// → true
_.flow([funcs])
Creates a function that returns the result of invoking the given functions
with the this
binding of the created function, where each successive
invocation is supplied the return value of the previous.
3.0.0
[funcs]
(…(Function|Function[])): Functions to invoke.(Function): Returns the new function.
function square(n) {
return n * n;
}
var addSquare = _.flow(_.add, square);
addSquare(1, 2);
// → 9
_.flowRight([funcs])
This method is like _.flow
except that it creates a function that
invokes the given functions from right to left.
3.0.0
[funcs]
(…(Function|Function[])): Functions to invoke.(Function): Returns the new function.
function square(n) {
return n * n;
}
var addSquare = _.flowRight(square, _.add);
addSquare(1, 2);
// → 9
_.identity(value)
This method returns the first argument given to it.
0.1.0
value
(*): Any value.(*): Returns value
.
var object = { 'user': 'fred' };
_.identity(object) === object;
// → true
_.iteratee([func=_.identity])
Creates a function that invokes func
with the arguments of the created
function. If func
is a property name, the created function returns the
property value for a given element. If func
is an array or object, the
created function returns true
for elements that contain the equivalent
source properties, otherwise it returns false
.
4.0.0
[func=_.identity]
(*): The value to convert to a callback.(Function): Returns the callback.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
// The `_.matches` iteratee shorthand.
_.filter(users, _.iteratee({ 'user': 'barney', 'active': true }));
// → [{ 'user': 'barney', 'age': 36, 'active': true }]
// The `_.matchesProperty` iteratee shorthand.
_.filter(users, _.iteratee(['user', 'fred']));
// → [{ 'user': 'fred', 'age': 40 }]
// The `_.property` iteratee shorthand.
_.map(users, _.iteratee('user'));
// → ['barney', 'fred']
// Create custom iteratee shorthands.
_.iteratee = _.wrap(_.iteratee, function(iteratee, func) {
return !_.isRegExp(func) ? iteratee(func) : function(string) {
return func.test(string);
};
});
_.filter(['abc', 'def'], /ef/);
// → ['def']
_.matches(source)
Creates a function that performs a partial deep comparison between a given
object and source
, returning true
if the given object has equivalent
property values, else false
. The created function is equivalent to
_.isMatch
with a source
partially applied.
Note: This method supports comparing the same values as _.isEqual
.
3.0.0
source
(Object): The object of property values to match.(Function): Returns the new function.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
_.filter(users, _.matches({ 'age': 40, 'active': false }));
// → [{ 'user': 'fred', 'age': 40, 'active': false }]
_.matchesProperty(path, srcValue)
Creates a function that performs a partial deep comparison between the
value at path
of a given object to srcValue
, returning true
if the
object value is equivalent, else false
.
Note: This method supports comparing the same values as _.isEqual
.
3.2.0
path
(Array|string): The path of the property to get.srcValue
(*): The value to match.(Function): Returns the new function.
var users = [
{ 'user': 'barney' },
{ 'user': 'fred' }
];
_.find(users, _.matchesProperty('user', 'fred'));
// → { 'user': 'fred' }
_.method(path, [args])
Creates a function that invokes the method at path
of a given object.
Any additional arguments are provided to the invoked method.
3.7.0
path
(Array|string): The path of the method to invoke.[args]
(…*): The arguments to invoke the method with.(Function): Returns the new function.
var objects = [
{ 'a': { 'b': _.constant(2) } },
{ 'a': { 'b': _.constant(1) } }
];
_.map(objects, _.method('a.b'));
// → [2, 1]
_.map(objects, _.method(['a', 'b']));
// → [2, 1]
_.methodOf(object, [args])
The opposite of _.method
; this method creates a function that invokes
the method at a given path of object
. Any additional arguments are
provided to the invoked method.
3.7.0
object
(Object): The object to query.[args]
(…*): The arguments to invoke the method with.(Function): Returns the new function.
var array = _.times(3, _.constant),
object = { 'a': array, 'b': array, 'c': array };
_.map(['a[2]', 'c[0]'], _.methodOf(object));
// → [2, 0]
_.map([['a', '2'], ['c', '0']], _.methodOf(object));
// → [2, 0]
_.mixin([object=lodash], source, [options={}], [options.chain=true])
Adds all own enumerable string keyed function properties of a source
object to the destination object. If object
is a function, then methods
are added to its prototype as well.
Note: Use _.runInContext
to create a pristine lodash
function to
avoid conflicts caused by modifying the original.
0.1.0
[object=lodash]
(Function|Object): The destination object.source
(Object): The object of functions to add.[options={}]
(Object): The options object.[options.chain=true]
(boolean): Specify whether mixins are chainable.(*): Returns object
.
function vowels(string) {
return _.filter(string, function(v) {
return /[aeiou]/i.test(v);
});
}
_.mixin({ 'vowels': vowels });
_.vowels('fred');
// → ['e']
_('fred').vowels().value();
// → ['e']
_.mixin({ 'vowels': vowels }, { 'chain': false });
_('fred').vowels();
// → ['e']
_.noConflict()
Reverts the _
variable to its previous value and returns a reference to
the lodash
function.
0.1.0
(Function): Returns the lodash
function.
var lodash = _.noConflict();
_.noop()
A no-operation function that returns undefined
regardless of the
arguments it receives.
2.3.0
var object = { 'user': 'fred' };
_.noop(object) === undefined;
// → true
_.nthArg([n=0])
Creates a function that returns its nth argument. If n
is negative,
the nth argument from the end is returned.
4.0.0
[n=0]
(number): The index of the argument to return.(Function): Returns the new function.
var func = _.nthArg(1);
func('a', 'b', 'c', 'd');
// → 'b'
var func = _.nthArg(-2);
func('a', 'b', 'c', 'd');
// → 'c'
_.over([iteratees=[_.identity]])
Creates a function that invokes iteratees
with the arguments it receives
and returns their results.
4.0.0
[iteratees=[_.identity]]
(…(Array|Array[]|Function|Function[]|Object|Object[]|string|string[])): The iteratees to invoke.(Function): Returns the new function.
var func = _.over(Math.max, Math.min);
func(1, 2, 3, 4);
// → [4, 1]
_.overEvery([predicates=[_.identity]])
Creates a function that checks if all of the predicates
return
truthy when invoked with the arguments it receives.
4.0.0
[predicates=[_.identity]]
(…(Array|Array[]|Function|Function[]|Object|Object[]|string|string[])): The predicates to check.(Function): Returns the new function.
var func = _.overEvery(Boolean, isFinite);
func('1');
// → true
func(null);
// → false
func(NaN);
// → false
_.overSome([predicates=[_.identity]])
Creates a function that checks if any of the predicates
return
truthy when invoked with the arguments it receives.
4.0.0
[predicates=[_.identity]]
(…(Array|Array[]|Function|Function[]|Object|Object[]|string|string[])): The predicates to check.(Function): Returns the new function.
var func = _.overSome(Boolean, isFinite);
func('1');
// → true
func(null);
// → true
func(NaN);
// → false
_.property(path)
Creates a function that returns the value at path
of a given object.
2.4.0
path
(Array|string): The path of the property to get.(Function): Returns the new function.
var objects = [
{ 'a': { 'b': 2 } },
{ 'a': { 'b': 1 } }
];
_.map(objects, _.property('a.b'));
// → [2, 1]
_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
// → [1, 2]
_.propertyOf(object)
The opposite of _.property
; this method creates a function that returns
the value at a given path of object
.
3.0.0
object
(Object): The object to query.(Function): Returns the new function.
var array = [0, 1, 2],
object = { 'a': array, 'b': array, 'c': array };
_.map(['a[2]', 'c[0]'], _.propertyOf(object));
// → [2, 0]
_.map([['a', '2'], ['c', '0']], _.propertyOf(object));
// → [2, 0]
_.range([start=0], end, [step=1])
Creates an array of numbers (positive and/or negative) progressing from
start
up to, but not including, end
. A step of -1
is used if a negative
start
is specified without an end
or step
. If end
is not specified,
it’s set to start
with start
then set to 0
.
Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.
0.1.0
[start=0]
(number): The start of the range.end
(number): The end of the range.[step=1]
(number): The value to increment or decrement by.(Array): Returns the new array of numbers.
_.range(4);
// → [0, 1, 2, 3]
_.range(-4);
// → [0, -1, -2, -3]
_.range(1, 5);
// → [1, 2, 3, 4]
_.range(0, 20, 5);
// → [0, 5, 10, 15]
_.range(0, -4, -1);
// → [0, -1, -2, -3]
_.range(1, 4, 0);
// → [1, 1, 1]
_.range(0);
// → []
_.rangeRight([start=0], end, [step=1])
This method is like _.range
except that it populates values in
descending order.
4.0.0
[start=0]
(number): The start of the range.end
(number): The end of the range.[step=1]
(number): The value to increment or decrement by.(Array): Returns the new array of numbers.
_.rangeRight(4);
// → [3, 2, 1, 0]
_.rangeRight(-4);
// → [-3, -2, -1, 0]
_.rangeRight(1, 5);
// → [4, 3, 2, 1]
_.rangeRight(0, 20, 5);
// → [15, 10, 5, 0]
_.rangeRight(0, -4, -1);
// → [-3, -2, -1, 0]
_.rangeRight(1, 4, 0);
// → [1, 1, 1]
_.rangeRight(0);
// → []
_.runInContext([context=root])
Create a new pristine lodash
function using the context
object.
1.1.0
[context=root]
(Object): The context object.(Function): Returns a new lodash
function.
_.mixin({ 'foo': _.constant('foo') });
var lodash = _.runInContext();
lodash.mixin({ 'bar': lodash.constant('bar') });
_.isFunction(_.foo);
// → true
_.isFunction(_.bar);
// → false
lodash.isFunction(lodash.foo);
// → false
lodash.isFunction(lodash.bar);
// → true
// Use `context` to mock `Date#getTime` use in `_.now`.
var mock = _.runInContext({
'Date': function() {
return { 'getTime': getTimeMock };
}
});
// Create a suped-up `defer` in Node.js.
var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;
_.times(n, [iteratee=_.identity])
Invokes the iteratee n
times, returning an array of the results of
each invocation. The iteratee is invoked with one argument; (index).
0.1.0
n
(number): The number of times to invoke iteratee
.[iteratee=_.identity]
(Function): The function invoked per iteration.(Array): Returns the array of results.
_.times(3, String);
// → ['0', '1', '2']
_.times(4, _.constant(true));
// → [true, true, true, true]
_.toPath(value)
Converts value
to a property path array.
4.0.0
value
(*): The value to convert.(Array): Returns the new property path array.
_.toPath('a.b.c');
// → ['a', 'b', 'c']
_.toPath('a[0].b.c');
// → ['a', '0', 'b', 'c']
var path = ['a', 'b', 'c'],
newPath = _.toPath(path);
console.log(newPath);
// → ['a', 'b', 'c']
console.log(path === newPath);
// → false
Properties
Methods