dojo/_base/lang.js

Dojo core is a powerful, lightweight library that makes common tasks quicker and easier. Animate elements, manipulate the DOM, and query with easy CSS syntax, all without sacrificing performance.

define(["./kernel", "../has", "../sniff"], function(dojo, has){
	// module:
	//		dojo/_base/lang

	has.add("bug-for-in-skips-shadowed", function(){
		// if true, the for-in iterator skips object properties that exist in Object's prototype (IE 6 - ?)
		for(var i in {toString: 1}){
			return 0;
		}
		return 1;
	});

	// Helper methods
	var _extraNames =
			has("bug-for-in-skips-shadowed") ?
				"hasOwnProperty.valueOf.isPrototypeOf.propertyIsEnumerable.toLocaleString.toString.constructor".split(".") : [],

		_extraLen = _extraNames.length,

		getProp = function(/*Array*/parts, /*Boolean*/create, /*Object*/context){
			if(!context){
				if(parts[0] && dojo.scopeMap[parts[0]]) {
					// Voodoo code from the old days where "dojo" or "dijit" maps to some special object
					// rather than just window.dojo
					context = dojo.scopeMap[parts.shift()][1];
				}else{
					context = dojo.global;
				}
			}

			try{
				for(var i = 0; i < parts.length; i++){
					var p = parts[i];
					// Fix for prototype pollution CVE-2021-23450
					if (p === '__proto__' || p === 'constructor') {
						return;
					}
					if(!(p in context)){
						if(create){
							context[p] = {};
						}else{
							return;		// return undefined
						}
					}
					context = context[p];
				}
				return context; // mixed
			}catch(e){
				// "p in context" throws an exception when context is a number, boolean, etc. rather than an object,
				// so in that corner case just return undefined (by having no return statement)
			}
		},

		opts = Object.prototype.toString,

		efficient = function(obj, offset, startWith){
			return (startWith||[]).concat(Array.prototype.slice.call(obj, offset||0));
		},

		_pattern = /\{([^\}]+)\}/g;

	// Module export
	var lang = {
		// summary:
		//		This module defines Javascript language extensions.

		// _extraNames: String[]
		//		Lists property names that must be explicitly processed during for-in iteration
		//		in environments that have has("bug-for-in-skips-shadowed") true.
		_extraNames:_extraNames,

		_mixin: function(dest, source, copyFunc){
			// summary:
			//		Copies/adds all properties of source to dest; returns dest.
			// 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?
			//		The process used to copy/add a property in source; defaults to the Javascript assignment operator.
			// returns:
			//		dest, as modified
			// description:
			//		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.
			var name, s, i, empty = {};
			for(name in source){
				// the (!(name in empty) || empty[name] !== s) condition avoids copying properties in "source"
				// inherited from Object.prototype.	 For example, if dest has a custom toString() method,
				// don't overwrite it with the toString() method that source inherited from Object.prototype
				s = source[name];
				if(!(name in dest) || (dest[name] !== s && (!(name in empty) || empty[name] !== s))){
					dest[name] = copyFunc ? copyFunc(s) : s;
				}
			}

			if(has("bug-for-in-skips-shadowed")){
				if(source){
					for(i = 0; i < _extraLen; ++i){
						name = _extraNames[i];
						s = source[name];
						if(!(name in dest) || (dest[name] !== s && (!(name in empty) || empty[name] !== s))){
							dest[name] = copyFunc ? copyFunc(s) : s;
						}
					}
				}
			}

			return dest; // Object
		},

		mixin: function(dest, sources){
			// summary:
			//		Copies/adds all properties of one or more sources to dest; returns dest.
			// 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".
			// returns: Object
			//		dest, as modified
			// description:
			//		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.
			// example:
			//		make a shallow copy of an object
			//	|	var copy = lang.mixin({}, source);
			// example:
			//		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!" });
			// example:
			//		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);

			if(!dest){ dest = {}; }
			for(var i = 1, l = arguments.length; i < l; i++){
				lang._mixin(dest, arguments[i]);
			}
			return dest; // Object
		},

		setObject: function(name, value, context){
			// summary:
			//		Set a property from a dot-separated string, such as "A.B.C"
			// description:
			//		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.
			// 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. Object to use as root of path. Defaults to
			//		`dojo.global`.
			// example:
			//		set the value of `foo.bar.baz`, regardless of whether
			//		intermediate objects already exist:
			//	| lang.setObject("foo.bar.baz", value);
			// example:
			//		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);

			var parts = name.split("."), p = parts.pop(), obj = getProp(parts, true, context);
			return obj && p ? (obj[p] = value) : undefined; // Object
		},

		getObject: function(name, create, context){
			// summary:
			//		Get a property from a dot-separated string, such as "A.B.C"
			// description:
			//		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.
			// name: String
			//		Path to an property, in the form "A.B.C".
			// create: Boolean?
			//		Optional. Defaults to `false`. If `true`, Objects will be
			//		created at any point along the 'path' that is undefined.
			// context: Object?
			//		Optional. Object to use as root of path. Defaults to
			//		'dojo.global'. Null may be passed.
			return !name ? context : getProp(name.split("."), create, context); // Object
		},

		exists: function(name, obj){
			// summary:
			//		determine if an object supports a given method
			// description:
			//		useful for longer api chains where you have to test each object in
			//		the chain. Useful for object and method detection.
			// name: String
			//		Path to an object, in the form "A.B.C".
			// obj: Object?
			//		Object to use as root of path. Defaults to
			//		'dojo.global'. Null may be passed.
			// example:
			//	| // 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
			return lang.getObject(name, false, obj) !== undefined; // Boolean
		},

		// Crockford (ish) functions

		isString: function(it){
			// summary:
			//		Return true if it is a String
			// it: anything
			//		Item to test.
			return (typeof it == "string" || it instanceof String); // Boolean
		},

		isArray: Array.isArray || function(it){
			// summary:
			//		Return true if it is an Array.
			// it: anything
			//		Item to test.
			return opts.call(it) == "[object Array]"; // Boolean
		},

		isFunction: function(it){
			// summary:
			//		Return true if it is a Function
			// it: anything
			//		Item to test.
			return opts.call(it) === "[object Function]";
		},

		isObject: function(it){
			// summary:
			//		Returns true if it is a JavaScript object (or an Array, a Function
			//		or null)
			// it: anything
			//		Item to test.
			return it !== undefined &&
				(it === null || typeof it == "object" || lang.isArray(it) || lang.isFunction(it)); // Boolean
		},

		isArrayLike: function(it){
			// summary:
			//		similar to isArray() but more permissive
			// it: anything
			//		Item to test.
			// returns:
			//		If it walks like a duck and quacks like a duck, return `true`
			// description:
			//		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().
			return !!it && // Boolean
				// keep out built-in constructors (Number, String, ...) which have length
				// properties
				!lang.isString(it) && !lang.isFunction(it) &&
				!(it.tagName && it.tagName.toLowerCase() == 'form') &&
				(lang.isArray(it) || isFinite(it.length));
		},

		isAlien: function(it){
			// summary:
			//		Returns true if it is a built-in function or some other kind of
			//		oddball that *should* report as a function but doesn't
			return it && !lang.isFunction(it) && /\{\s*\[native code\]\s*\}/.test(String(it)); // Boolean
		},

		extend: function(ctor, props){
			// summary:
			//		Adds all properties and methods of props to constructor's
			//		prototype, making them available to all instances created with
			//		constructor.
			// ctor: Object
			//		Target constructor to extend.
			// props: Object
			//		One or more objects to mix into ctor.prototype
			for(var i=1, l=arguments.length; i<l; i++){
				lang._mixin(ctor.prototype, arguments[i]);
			}
			return ctor; // Object
		},

		_hitchArgs: function(scope, method){
			var pre = lang._toArray(arguments, 2);
			var named = lang.isString(method);
			return function(){
				// arrayify arguments
				var args = lang._toArray(arguments);
				// locate our method
				var f = named ? (scope||dojo.global)[method] : method;
				// invoke with collected args
				return f && f.apply(scope || this, pre.concat(args)); // mixed
			}; // Function
		},

		hitch: function(scope, method){
			// summary:
			//		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.
			// 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.
			// example:
			//	|	lang.hitch(foo, "bar")();
			//		runs foo.bar() in the scope of foo
			// example:
			//	|	lang.hitch(foo, myFunction);
			//		returns a function that runs myFunction in the scope of foo
			// example:
			//		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"
			// example:
			//	|	var foo = { bar: 2 };
			//	|	lang.hitch(foo, function(){ this.bar = 10; })();
			//		execute an anonymous function in scope of foo
			if(arguments.length > 2){
				return lang._hitchArgs.apply(dojo, arguments); // Function
			}
			if(!method){
				method = scope;
				scope = null;
			}
			if(lang.isString(method)){
				scope = scope || dojo.global;
				if(!scope[method]){ throw(['lang.hitch: scope["', method, '"] is null (scope="', scope, '")'].join('')); }
				return function(){ return scope[method].apply(scope, arguments || []); }; // Function
			}
			return !scope ? method : function(){ return method.apply(scope, arguments || []); }; // Function
		},

		delegate: (function(){
			// boodman/crockford delegation w/ cornford optimization
			function TMP(){}
			return function(obj, props){
				TMP.prototype = obj;
				var tmp = new TMP();
				TMP.prototype = null;
				if(props){
					lang._mixin(tmp, props);
				}
				return tmp; // Object
			};
		})(),
		/*=====
		delegate: function(obj, props){
			// summary:
			//		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.
			// description:
			//		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.
			// 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
			// returns:
			//		an Object of anonymous type
			// example:
			//	|	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
		},
		=====*/

		_toArray: has("ie") ?
			(function(){
				function slow(obj, offset, startWith){
					var arr = startWith||[];
					for(var x = offset || 0; x < obj.length; x++){
						arr.push(obj[x]);
					}
					return arr;
				}
				return function(obj){
					return ((obj.item) ? slow : efficient).apply(this, arguments);
				};
			})() : efficient,
		/*=====
		 _toArray: function(obj, offset, startWith){
			 // summary:
			 //		Converts an array-like object (i.e. arguments, DOMCollection) to an
			 //		array. Returns a new Array with the elements of obj.
			 // 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?
			 //		the location in obj to start iterating from. Defaults to 0.
			 //		Optional.
			 // startWith: Array?
			 //		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.
		 },
		 =====*/

		partial: function(/*Function|String*/ method /*, ...*/){
			// summary:
			//		similar to hitch() except that the scope object is left to be
			//		whatever the execution context eventually becomes.
			// description:
			//		Calling lang.partial is the functional equivalent of calling:
			//		|	lang.hitch(null, funcName, ...);
			// method:
			//		The function to "wrap"
			var arr = [ null ];
			return lang.hitch.apply(dojo, arr.concat(lang._toArray(arguments))); // Function
		},

		clone: function(/*anything*/ src){
			// summary:
			//		Clones objects (including DOM nodes) and all children.
			//		Warning: do not clone cyclic structures.
			// src:
			//		The object to clone
			if(!src || typeof src != "object" || lang.isFunction(src)){
				// null, undefined, any non-object, or function
				return src;	// anything
			}
			if(src.nodeType && "cloneNode" in src){
				// DOM Node
				return src.cloneNode(true); // Node
			}
			if(src instanceof Date){
				// Date
				return new Date(src.getTime());	// Date
			}
			if(src instanceof RegExp){
				// RegExp
				return new RegExp(src);   // RegExp
			}
			var r, i, l;
			if(lang.isArray(src)){
				// array
				r = [];
				for(i = 0, l = src.length; i < l; ++i){
					if(i in src){
						r[i] = lang.clone(src[i]);
					}
				}
				// we don't clone functions for performance reasons
				//		}else if(d.isFunction(src)){
				//			// function
				//			r = function(){ return src.apply(this, arguments); };
			}else{
				// generic objects
				r = src.constructor ? new src.constructor() : {};
			}
			return lang._mixin(r, src, lang.clone);
		},


		trim: String.prototype.trim ?
			function(str){ return str.trim(); } :
			function(str){ return str.replace(/^\s\s*/, '').replace(/\s\s*$/, ''); },
		/*=====
		 trim: function(str){
			 // summary:
			 //		Trims whitespace from both sides of the string
			 // str: String
			 //		String to be trimmed
			 // returns: String
			 //		Returns the trimmed string
			 // description:
			 //		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](http://blog.stevenlevithan.com/archives/faster-trim-javascript)
			 //		Uses String.prototype.trim instead, if available.
			 //		The fastest but longest version of this function is located at
			 //		lang.string.trim()
		 },
		 =====*/

		replace: function(tmpl, map, pattern){
			// summary:
			//		Performs parameterized substitutions on a string. Throws an
			//		exception if any parameter is unmatched.
			// 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 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: String
			//		Returns the substituted string.
			// example:
			//	|	// 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!
			// example:
			//	|	// uses an array for substitutions:
			//	|	lang.replace("Hello, {0} {2}!",
			//	|		["Robert", "X", "Cringely"]);
			//	|	// returns: Hello, Robert Cringely!
			// example:
			//	|	// 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.
			// example:
			//	|	// uses an alternative PHP-like pattern for substitutions:
			//	|	lang.replace("Hello, ${0} ${2}!",
			//	|		["Robert", "X", "Cringely"], /\$\{([^\}]+)\}/g);
			//	|	// returns: Hello, Robert Cringely!

			return tmpl.replace(pattern || _pattern, lang.isFunction(map) ?
				map : function(_, k){ return lang.getObject(k, false, map); });
		}
	};

	has("extend-dojo") && lang.mixin(dojo, lang);

	return lang;
});