lodash v4.11.23.10.12.4.21.3.1

_.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.

Since

3.0.0

Arguments

1. array (Array): The array to process.
2. [size=1] (number): The length of each chunk

Returns

(Array): Returns the new array containing chunks.

Example

_.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.

Since

0.1.0

Arguments

1. array (Array): The array to compact.

Returns

(Array): Returns the new array of filtered values.

Example

_.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.

Since

4.0.0

Arguments

1. array (Array): The array to concatenate.
2. [values] (…*): The values to concatenate.

Returns

(Array): Returns the new concatenated array.

Example

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.

Since

0.1.0

Arguments

1. array (Array): The array to inspect.
2. [values] (…Array): The values to exclude.

Returns

(Array): Returns the new array of filtered values.

Example

_.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).

Since

4.0.0

Arguments

1. array (Array): The array to inspect.
2. [values] (…Array): The values to exclude.
3. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(Array): Returns the new array of filtered values.

Example

_.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).

Since

4.0.0

Arguments

1. array (Array): The array to inspect.
2. [values] (…Array): The values to exclude.
3. [comparator] (Function): The comparator invoked per element.

Returns

(Array): Returns the new array of filtered values.

Example

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.

Since

0.5.0

Arguments

1. array (Array): The array to query.
2. [n=1] (number): The number of elements to drop.

Returns

(Array): Returns the slice of array.

Example

_.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.

Since

3.0.0

Arguments

1. array (Array): The array to query.
2. [n=1] (number): The number of elements to drop.

Returns

(Array): Returns the slice of array.

Example

_.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).

Since

3.0.0

Arguments

1. array (Array): The array to query.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the slice of array.

Example

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).

Since

3.0.0

Arguments

1. array (Array): The array to query.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the slice of array.

Example

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.

Since

3.2.0

Arguments

1. array (Array): The array to fill.
2. value (*): The value to fill array with.
3. [start=0] (number): The start position.
4. [end=array.length] (number): The end position.

Returns

(Array): Returns array.

Example

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.

Since

1.1.0

Arguments

1. array (Array): The array to search.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(number): Returns the index of the found element, else -1.

Example

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.

Since

2.0.0

Arguments

1. array (Array): The array to search.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(number): Returns the index of the found element, else -1.

Example

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.

Since

0.1.0

Arguments

1. array (Array): The array to flatten.

Returns

(Array): Returns the new flattened array.

Example

_.flatten([1, [2, [3, [4]], 5]]);
// → [1, 2, [3, [4]], 5]

_.flattenDeep(array)

Ⓢ Ⓝ

Recursively flattens array.

Since

3.0.0

Arguments

1. array (Array): The array to flatten.

Returns

(Array): Returns the new flattened array.

Example

_.flattenDeep([1, [2, [3, [4]], 5]]);
// → [1, 2, 3, 4, 5]

_.flattenDepth(array, [depth=1])

Ⓢ Ⓝ

Recursively flatten array up to depth times.

Since

4.4.0

Arguments

1. array (Array): The array to flatten.
2. [depth=1] (number): The maximum recursion depth.

Returns

(Array): Returns the new flattened array.

Example

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.

Since

4.0.0

Arguments

1. pairs (Array): The key-value pairs.

Returns

(Object): Returns the new object.

Example

_.fromPairs([['fred', 30], ['barney', 40]]);
// → { 'fred': 30, 'barney': 40 }

_.head(array)

Ⓢ Ⓝ

Gets the first element of array.

Since

0.1.0

Aliases

_.first

Arguments

1. array (Array): The array to query.

Returns

(*): Returns the first element of array.

Example

_.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.

Since

0.1.0

Arguments

1. array (Array): The array to search.
2. value (*): The value to search for.
3. [fromIndex=0] (number): The index to search from.

Returns

(number): Returns the index of the matched value, else -1.

Example

_.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.

Since

0.1.0

Arguments

1. array (Array): The array to query.

Returns

(Array): Returns the slice of array.

Example

_.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.

Since

0.1.0

Arguments

1. [arrays] (…Array): The arrays to inspect.

Returns

(Array): Returns the new array of intersecting values.

Example

_.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).

Since

4.0.0

Arguments

1. [arrays] (…Array): The arrays to inspect.
2. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(Array): Returns the new array of intersecting values.

Example

_.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).

Since

4.0.0

Arguments

1. [arrays] (…Array): The arrays to inspect.
2. [comparator] (Function): The comparator invoked per element.

Returns

(Array): Returns the new array of intersecting values.

Example

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.

Since

4.0.0

Arguments

1. array (Array): The array to convert.
2. [separator=','] (string): The element separator.

Returns

(string): Returns the joined string.

Example

_.join(['a', 'b', 'c'], '~');
// → 'a~b~c'

_.last(array)

Ⓢ Ⓝ

Gets the last element of array.

Since

0.1.0

Arguments

1. array (Array): The array to query.

Returns

(*): Returns the last element of array.

Example

_.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.

Since

0.1.0

Arguments

1. array (Array): The array to search.
2. value (*): The value to search for.
3. [fromIndex=array.length-1] (number): The index to search from.

Returns

(number): Returns the index of the matched value, else -1.

Example

_.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.

Since

4.11.0

Arguments

1. array (Array): The array to query.
2. [n=0] (number): The index of the element to return.

Returns

(*): Returns the nth element of array.

Example

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.

Since

2.0.0

Arguments

1. array (Array): The array to modify.
2. [values] (…*): The values to remove.

Returns

(Array): Returns array.

Example

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.

Since

4.0.0

Arguments

1. array (Array): The array to modify.
2. values (Array): The values to remove.

Returns

(Array): Returns array.

Example

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.

Since

4.0.0

Arguments

1. array (Array): The array to modify.
2. values (Array): The values to remove.
3. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(Array): Returns array.

Example

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.

Since

4.6.0

Arguments

1. array (Array): The array to modify.
2. values (Array): The values to remove.
3. [comparator] (Function): The comparator invoked per element.

Returns

(Array): Returns array.

Example

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.

Since

3.0.0

Arguments

1. array (Array): The array to modify.
2. [indexes] (…(number|number[])): The indexes of elements to remove.

Returns

(Array): Returns the new array of removed elements.

Example

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.

Since

2.0.0

Arguments

1. array (Array): The array to modify.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the new array of removed elements.

Example

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.

Since

4.0.0

Arguments

1. array (Array): The array to modify.

Returns

(Array): Returns array.

Example

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.

Since

3.0.0

Arguments

1. array (Array): The array to slice.
2. [start=0] (number): The start position.
3. [end=array.length] (number): The end position.

Returns

(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.

Since

0.1.0

Arguments

1. array (Array): The sorted array to inspect.
2. value (*): The value to evaluate.

Returns

(number): Returns the index at which value should be inserted into array.

Example

_.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).

Since

4.0.0

Arguments

1. array (Array): The sorted array to inspect.
2. value (*): The value to evaluate.
3. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(number): Returns the index at which value should be inserted into array.

Example

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.

Since

4.0.0

Arguments

1. array (Array): The array to search.
2. value (*): The value to search for.

Returns

(number): Returns the index of the matched value, else -1.

Example

_.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.

Since

3.0.0

Arguments

1. array (Array): The sorted array to inspect.
2. value (*): The value to evaluate.

Returns

(number): Returns the index at which value should be inserted into array.

Example

_.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).

Since

4.0.0

Arguments

1. array (Array): The sorted array to inspect.
2. value (*): The value to evaluate.
3. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(number): Returns the index at which value should be inserted into array.

Example

// 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.

Since

4.0.0

Arguments

1. array (Array): The array to search.
2. value (*): The value to search for.

Returns

(number): Returns the index of the matched value, else -1.

Example

_.sortedLastIndexOf([1, 1, 2, 2], 2);
// → 3

_.sortedUniq(array)

Ⓢ Ⓝ

This method is like _.uniq except that it’s designed and optimized for sorted arrays.

Since

4.0.0

Arguments

1. array (Array): The array to inspect.

Returns

(Array): Returns the new duplicate free array.

Example

_.sortedUniq([1, 1, 2]);
// → [1, 2]

_.sortedUniqBy(array, [iteratee])

Ⓢ Ⓝ

This method is like _.uniqBy except that it’s designed and optimized for sorted arrays.

Since

4.0.0

Arguments

1. array (Array): The array to inspect.
2. [iteratee] (Function): The iteratee invoked per element.

Returns

(Array): Returns the new duplicate free array.

Example

_.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.

Since

4.0.0

Arguments

1. array (Array): The array to query.

Returns

(Array): Returns the slice of array.

Example

_.tail([1, 2, 3]);
// → [2, 3]

_.take(array, [n=1])

Ⓢ Ⓝ

Creates a slice of array with n elements taken from the beginning.

Since

0.1.0

Arguments

1. array (Array): The array to query.
2. [n=1] (number): The number of elements to take.

Returns

(Array): Returns the slice of array.

Example

_.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.

Since

3.0.0

Arguments

1. array (Array): The array to query.
2. [n=1] (number): The number of elements to take.

Returns

(Array): Returns the slice of array.

Example

_.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).

Since

3.0.0

Arguments

1. array (Array): The array to query.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the slice of array.

Example

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).

Since

3.0.0

Arguments

1. array (Array): The array to query.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the slice of array.

Example

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.

Since

0.1.0

Arguments

1. [arrays] (…Array): The arrays to inspect.

Returns

(Array): Returns the new array of combined values.

Example

_.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).

Since

4.0.0

Arguments

1. [arrays] (…Array): The arrays to inspect.
2. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(Array): Returns the new array of combined values.

Example

_.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).

Since

4.0.0

Arguments

1. [arrays] (…Array): The arrays to inspect.
2. [comparator] (Function): The comparator invoked per element.

Returns

(Array): Returns the new array of combined values.

Example

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.

Since

0.1.0

Arguments

1. array (Array): The array to inspect.

Returns

(Array): Returns the new duplicate free array.

Example

_.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).

Since

4.0.0

Arguments

1. array (Array): The array to inspect.
2. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(Array): Returns the new duplicate free array.

Example

_.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).

Since

4.0.0

Arguments

1. array (Array): The array to inspect.
2. [comparator] (Function): The comparator invoked per element.

Returns

(Array): Returns the new duplicate free array.

Example

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.

Since

1.2.0

Arguments

1. array (Array): The array of grouped elements to process.

Returns

(Array): Returns the new array of regrouped elements.

Example

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).

Since

3.8.0

Arguments

1. array (Array): The array of grouped elements to process.
2. [iteratee=_.identity] (Function): The function to combine regrouped values.

Returns

(Array): Returns the new array of regrouped elements.

Example

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.

Since

0.1.0

Arguments

1. array (Array): The array to filter.
2. [values] (…*): The values to exclude.

Returns

(Array): Returns the new array of filtered values.

Example

_.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.

Since

2.4.0

Arguments

1. [arrays] (…Array): The arrays to inspect.

Returns

(Array): Returns the new array of values.

Example

_.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).

Since

4.0.0

Arguments

1. [arrays] (…Array): The arrays to inspect.
2. [iteratee=_.identity] (Array|Function|Object|string): The iteratee invoked per element.

Returns

(Array): Returns the new array of values.

Example

_.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).

Since

4.0.0

Arguments

1. [arrays] (…Array): The arrays to inspect.
2. [comparator] (Function): The comparator invoked per element.

Returns

(Array): Returns the new array of values.

Example

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.

Since

0.1.0

Arguments

1. [arrays] (…Array): The arrays to process.

Returns

(Array): Returns the new array of grouped elements.

Example

_.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.

Since

0.4.0

Arguments

1. [props=[]] (Array): The property identifiers.
2. [values=[]] (Array): The property values.

Returns

(Object): Returns the new object.

Example

_.zipObject(['a', 'b'], [1, 2]);
// → { 'a': 1, 'b': 2 }

_.zipObjectDeep([props=[]], [values=[]])

Ⓢ Ⓝ

This method is like _.zipObject except that it supports property paths.

Since

4.1.0

Arguments

1. [props=[]] (Array): The property identifiers.
2. [values=[]] (Array): The property values.

Returns

(Object): Returns the new object.

Example

_.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).

Since

3.8.0

Arguments

1. [arrays] (…Array): The arrays to process.
2. [iteratee=_.identity] (Function): The function to combine grouped values.

Returns

(Array): Returns the new array of grouped elements.

Example

_.zipWith([1, 2], [10, 20], [100, 200], function(a, b, c) {
  return a + b + c;
});
// → [111, 222]

_.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).

Since

0.5.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Array|Function|Object|string): The iteratee to transform keys.

Returns

(Object): Returns the composed aggregate object.

Example

_.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).

Since

0.1.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(boolean): Returns true if all elements pass the predicate check, else false.

Example

_.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).

Since

0.1.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the new filtered array.

Example

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).

Since

0.1.0

Arguments

1. collection (Array|Object): The collection to search.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(*): Returns the matched element, else undefined.

Example

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.

Since

2.0.0

Arguments

1. collection (Array|Object): The collection to search.
2. [predicate=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(*): Returns the matched element, else undefined.

Example

_.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).

Since

4.0.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the new flattened array.

Example

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.

Since

4.7.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Array|Function|Object|string): The function invoked per iteration.

Returns

(Array): Returns the new flattened array.

Example

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.

Since

4.7.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Array|Function|Object|string): The function invoked per iteration.
3. [depth=1] (number): The maximum recursion depth.

Returns

(Array): Returns the new flattened array.

Example

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.

Since

0.1.0

Aliases

_.each

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Function): The function invoked per iteration.

Returns

(*): Returns collection.

Example

_([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.

Since

2.0.0

Aliases

_.eachRight

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Function): The function invoked per iteration.

Returns

(*): Returns collection.

Example

_.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).

Since

0.1.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. [iteratee=_.identity] (Array|Function|Object|string): The iteratee to transform keys.

Returns

(Object): Returns the composed aggregate object.

Example

_.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.

Since

0.1.0

Arguments

1. collection (Array|Object|string): The collection to search.
2. value (*): The value to search for.
3. [fromIndex=0] (number): The index to search from.

Returns

(boolean): Returns true if value is found, else false.

Example

_.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.

Since

4.0.0

Arguments

1. collection (Array|Object): The collection to iterate over.
2. path (Array|Function|string): The path of the method to invoke or the function invoked per iteration.
3. [args] (…*): The arguments to invoke each method with.

Returns

(Array): Returns the array of results.

Example

_.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])