This module defines Javascript language extensions.
See the dojo/_base/lang reference documentation for more information.
Lists property names that must be explicitly processed during for-in iteration in environments that have has("bug-for-in-skips-shadowed") true.
Parameter | Type | Description |
---|---|---|
scope | undefined | |
method | undefined |
Copies/adds all properties of source to dest; returns dest.
All properties, including functions (sometimes termed "methods"), excluding any non-standard extensions found in Object.prototype, are copied/added to dest. Copying/adding each particular property is delegated to copyFunc (if any); copyFunc defaults to the Javascript assignment operator if not provided. Notice that by default, _mixin executes a so-called "shallow copy" and aggregate types are copied/added by reference.
Parameter | Type | Description |
---|---|---|
dest | Object | The object to which to copy/add all properties contained in source. |
source | Object | The object from which to draw all properties to copy into dest. |
copyFunc | Function |
Optional The process used to copy/add a property in source; defaults to the Javascript assignment operator. |
dest, as modified
Converts an array-like object (i.e. arguments, DOMCollection) to an array. Returns a new Array with the elements of obj.
Parameter | Type | Description |
---|---|---|
obj | Object | the object to "arrayify". We expect the object to have, at a minimum, a length property which corresponds to integer-indexed properties. |
offset | Number |
Optional the location in obj to start iterating from. Defaults to 0. Optional. |
startWith | Array |
Optional An array to pack with the properties of obj. If provided, properties in obj are appended at the end of startWith and startWith is the returned array. |
Clones objects (including DOM nodes) and all children. Warning: do not clone cyclic structures.
Parameter | Type | Description |
---|---|---|
src | anything | The object to clone |
The object to clone
Returns a new object which "looks" to obj for properties which it does not have a value for. Optionally takes a bag of properties to seed the returned object with initially.
This is a small implementation of the Boodman/Crockford delegation pattern in JavaScript. An intermediate object constructor mediates the prototype chain for the returned object, using it to delegate down to obj for property lookup when object-local lookup fails. This can be thought of similarly to ES4's "wrap", save that it does not act on types but rather on pure objects.
Parameter | Type | Description |
---|---|---|
obj | Object | The object to delegate to for properties not found directly on the return object or in props. |
props | Object... | an object containing properties to assign to the returned object |
an Object of anonymous type
var foo = { bar: "baz" }; var thinger = lang.delegate(foo, { thud: "xyzzy"}); thinger.bar == "baz"; // delegated to foo foo.thud == undefined; // by definition thinger.thud == "xyzzy"; // mixed in from props foo.bar = "thonk"; thinger.bar == "thonk"; // still delegated to foo's bar
determine if an object supports a given method
useful for longer api chains where you have to test each object in the chain. Useful for object and method detection.
Parameter | Type | Description |
---|---|---|
name | String | Path to an object, in the form "A.B.C". |
obj | Object |
Optional Object to use as root of path. Defaults to 'dojo.global'. Null may be passed. |
// define an object var foo = { bar: { } }; // search the global scope lang.exists("foo.bar"); // true lang.exists("foo.bar.baz"); // false // search from a particular scope lang.exists("bar", foo); // true lang.exists("bar.baz", foo); // false
Adds all properties and methods of props to constructor's prototype, making them available to all instances created with constructor.
Parameter | Type | Description |
---|---|---|
ctor | Object | Target constructor to extend. |
props | Object | One or more objects to mix into ctor.prototype |
Target constructor to extend.
Get a property from a dot-separated string, such as "A.B.C"
Useful for longer api chains where you have to test each object in the chain, or when you have an object reference in string format.
Parameter | Type | Description |
---|---|---|
name | String | Path to an property, in the form "A.B.C". |
create | Boolean |
Optional Optional. Defaults to |
context | Object |
Optional Optional. Object to use as root of path. Defaults to 'dojo.global'. Null may be passed. |
Returns a function that will only ever execute in the given scope. This allows for easy use of object member functions in callbacks and other places in which the "this" keyword may otherwise not reference the expected scope. Any number of default positional arguments may be passed as parameters beyond "method". Each of these values will be used to "placehold" (similar to curry) for the hitched function.
Parameter | Type | Description |
---|---|---|
scope | Object | The scope to use when method executes. If method is a string, scope is also the object containing method. |
method | Function | String... | A function to be hitched to scope, or the name of the method in scope to be hitched. |
lang.hitch(foo, "bar")();
runs foo.bar() in the scope of foo
lang.hitch(foo, myFunction);
returns a function that runs myFunction in the scope of foo
Expansion on the default positional arguments passed along from hitch. Passed args are mixed first, additional args after.
var foo = { bar: function(a, b, c){ console.log(a, b, c); } }; var fn = lang.hitch(foo, "bar", 1, 2); fn(3); // logs "1, 2, 3"
var foo = { bar: 2 }; lang.hitch(foo, function(){ this.bar = 10; })();
execute an anonymous function in scope of foo
Returns true if it is a built-in function or some other kind of oddball that should report as a function but doesn't
Parameter | Type | Description |
---|---|---|
it | undefined |
Return true if it is an Array. Does not work on Arrays created in other windows.
Parameter | Type | Description |
---|---|---|
it | anything | Item to test. |
similar to isArray() but more permissive
Doesn't strongly test for "arrayness". Instead, settles for "isn't a string or number and has a length property". Arguments objects and DOM collections will return true when passed to isArrayLike(), but will return false when passed to isArray().
Parameter | Type | Description |
---|---|---|
it | anything | Item to test. |
If it walks like a duck and quacks like a duck, return true
Return true if it is a Function
Parameter | Type | Description |
---|---|---|
it | anything | Item to test. |
Returns true if it is a JavaScript object (or an Array, a Function or null)
Parameter | Type | Description |
---|---|---|
it | anything | Item to test. |
Return true if it is a String
Parameter | Type | Description |
---|---|---|
it | anything | Item to test. |
Copies/adds all properties of one or more sources to dest; returns dest.
All properties, including functions (sometimes termed "methods"), excluding any non-standard extensions found in Object.prototype, are copied/added from sources to dest. sources are processed left to right. The Javascript assignment operator is used to copy/add each property; therefore, by default, mixin executes a so-called "shallow copy" and aggregate types are copied/added by reference.
Parameter | Type | Description |
---|---|---|
dest | Object | The object to which to copy/add all properties contained in source. If dest is falsy, then a new object is manufactured before copying/adding properties begins. |
sources | Object... | One of more objects from which to draw all properties to copy into dest. sources are processed left-to-right and if more than one of these objects contain the same property name, the right-most value "wins". |
dest, as modified
make a shallow copy of an object
var copy = lang.mixin({}, source);
many class constructors often take an object which specifies
values to be configured on the object. In this case, it is
often simplest to call lang.mixin
on the this
object:
declare("acme.Base", null, { constructor: function(properties){ // property configuration: lang.mixin(this, properties); console.log(this.quip); // ... }, quip: "I wasn't born yesterday, you know - I've seen movies.", // ... }); // create an instance of the class and configure it var b = new acme.Base({quip: "That's what it does!" });
copy in properties from multiple objects
var flattened = lang.mixin( { name: "Frylock", braces: true }, { name: "Carl Brutanananadilewski" } ); // will print "Carl Brutanananadilewski" console.log(flattened.name); // will print "true" console.log(flattened.braces);
similar to hitch() except that the scope object is left to be whatever the execution context eventually becomes.
Calling lang.partial is the functional equivalent of calling:
lang.hitch(null, funcName, ...);
Parameter | Type | Description |
---|---|---|
method | Function | String | The function to "wrap" |
Performs parameterized substitutions on a string. Throws an exception if any parameter is unmatched.
Parameter | Type | Description |
---|---|---|
tmpl | String | String to be used as a template. |
map | Object | Function | If an object, it is used as a dictionary to look up substitutions. If a function, it is called for every substitution with following parameters: a whole match, a name, an offset, and the whole template string (see https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/String/replace for more details). |
pattern | RegEx |
Optional Optional regular expression objects that overrides the default pattern. Must be global and match one item. The default is: /{([^}]+)}/g, which matches patterns like that: "{xxx}", where "xxx" is any sequence of characters, which doesn't include "}". |
Returns the substituted string.
// uses a dictionary for substitutions: lang.replace("Hello, {name.first} {name.last} AKA {nick}!", { nick: "Bob", name: { first: "Robert", middle: "X", last: "Cringely" } }); // returns: Hello, Robert Cringely AKA Bob!
// uses an array for substitutions: lang.replace("Hello, {0} {2}!", ["Robert", "X", "Cringely"]); // returns: Hello, Robert Cringely!
// uses a function for substitutions: function sum(a){ var t = 0; arrayforEach(a, function(x){ t += x; }); return t; } lang.replace( "{count} payments averaging {avg} USD per payment.", lang.hitch( { payments: [11, 16, 12] }, function(_, key){ switch(key){ case "count": return this.payments.length; case "min": return Math.min.apply(Math, this.payments); case "max": return Math.max.apply(Math, this.payments); case "sum": return sum(this.payments); case "avg": return sum(this.payments) / this.payments.length; } } ) ); // prints: 3 payments averaging 13 USD per payment.
// uses an alternative PHP-like pattern for substitutions: lang.replace("Hello, ${0} ${2}!", ["Robert", "X", "Cringely"], /\$\{([^\}]+)\}/g); // returns: Hello, Robert Cringely!
Set a property from a dot-separated string, such as "A.B.C"
Useful for longer api chains where you have to test each object in
the chain, or when you have an object reference in string format.
Objects are created as needed along path
. Returns the passed
value if setting is successful or undefined
if not.
Parameter | Type | Description |
---|---|---|
name | String | Path to a property, in the form "A.B.C". |
value | anything | value or object to place at location given by name |
context | Object |
Optional Optional. Object to use as root of path. Defaults to
|
set the value of foo.bar.baz
, regardless of whether
intermediate objects already exist:
lang.setObject("foo.bar.baz", value);
without lang.setObject
, we often see code like this:
// ensure that intermediate objects are available if(!obj["parent"]){ obj.parent = {}; } if(!obj.parent["child"]){ obj.parent.child = {}; } // now we can safely set the property obj.parent.child.prop = "some value";
whereas with lang.setObject
, we can shorten that to:
lang.setObject("parent.child.prop", "some value", obj);
Trims whitespace from both sides of the string
This version of trim() was selected for inclusion into the base due to its compact size and relatively good performance (see Steven Levithan's blog Uses String.prototype.trim instead, if available. The fastest but longest version of this function is located at lang.string.trim()
Parameter | Type | Description |
---|---|---|
str | String | String to be trimmed |
Returns the trimmed string