| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423 | <!DOCTYPE html><html><head>  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  <title>The source code</title>  <link href="../resources/prettify/prettify.css" type="text/css" rel="stylesheet" />  <script type="text/javascript" src="../resources/prettify/prettify.js"></script>  <style type="text/css">    .highlight { display: block; background-color: #ddd; }  </style>  <script type="text/javascript">    function highlight() {      document.getElementById(location.hash.replace(/#/, "")).className = "highlight";    }  </script></head><body onload="prettyPrint(); highlight();">  <pre class="prettyprint lang-js"><span id='Object'>/**</span> * @class Object * * Creates an object wrapper. * * The Object constructor creates an object wrapper for the given value. If the value is null or * undefined, it will create and return an empty object, otherwise, it will return an object of a type * that corresponds to the given value. * * When called in a non-constructor context, Object behaves identically. * * # Using Object given undefined and null types * * The following examples store an empty Object object in o: *     var o = new Object(); * *     var o = new Object(undefined); * *     var o = new Object(null); * * # Using Object to create Boolean objects * * The following examples store Boolean objects in o: * *     // equivalent to o = new Boolean(true); *     var o = new Object(true); * *     // equivalent to o = new Boolean(false); *     var o = new Object(Boolean()); * * <div class="notice"> * Documentation for this class comes from <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object">MDN</a> * and is available under <a href="http://creativecommons.org/licenses/by-sa/2.0/">Creative Commons: Attribution-Sharealike license</a>. * </div> */<span id='Object-method-constructor'>/**</span> * @method constructor * Creates new Object. * @param {Object} [value] The value to wrap. *///Properties<span id='Object-property-prototype'>/**</span> * @property prototype * Allows the addition of properties to all objects of type Object. *///Methods<span id='Object-method-hasOwnProperty'>/**</span> * @method hasOwnProperty * Returns a boolean indicating whether an object contains the specified property as a direct property * of that object and not inherited through the prototype chain. * * Every object descended from `Object` inherits the `hasOwnProperty` method. This method can be used * to determine whether an object has the specified property as a direct property of that object; * unlike the `in` operator, this method does not check down the object's prototype chain. * * The following example determines whether the o object contains a property named prop: * *     o = new Object(); *     o.prop = 'exists'; * *     function changeO() { *         o.newprop = o.prop; *         delete o.prop; *     } * *     o.hasOwnProperty('prop');   //returns true *     changeO(); *     o.hasOwnProperty('prop');   //returns false * * The following example differentiates between direct properties and properties inherited through the * prototype chain: * *     o = new Object(); *     o.prop = 'exists'; *     o.hasOwnProperty('prop');             // returns true *     o.hasOwnProperty('toString');         // returns false *     o.hasOwnProperty('hasOwnProperty');   // returns false * * The following example shows how to iterate over the properties of an object without executing on * inherit properties. * *     var buz = { *         fog: 'stack' *     }; * *     for (var name in buz) { *         if (buz.hasOwnProperty(name)) { *             alert("this is fog (" + name + ") for sure. Value: " + buz[name]); *         } *         else { *             alert(name); // toString or something else *         } *     } * * @param {String} prop The name of the property to test. * @return {Boolean} Returns true if object contains specified property; else * returns false. */<span id='Object-method-isPrototypeOf'>/**</span> * @method isPrototypeOf * Returns a boolean indication whether the specified object is in the prototype chain of the object * this method is called upon. * * `isPrototypeOf` allows you to check whether or not an object exists within another object's * prototype chain. * * For example, consider the following prototype chain: * *     function Fee() { *         // . . . *     } * *     function Fi() { *         // . . . *     } *     Fi.prototype = new Fee(); * *     function Fo() { *         // . . . *     } *     Fo.prototype = new Fi(); * *     function Fum() { *         // . . . *     } *     Fum.prototype = new Fo(); * * Later on down the road, if you instantiate `Fum` and need to check if `Fi`'s prototype exists * within the `Fum` prototype chain, you could do this: * *     var fum = new Fum(); *     . . . * *     if (Fi.prototype.isPrototypeOf(fum)) { *     // do something safe *     } * * This, along with the `instanceof` operator particularly comes in handy if you have code that can * only function when dealing with objects descended from a specific prototype chain, e.g., to * guarantee that certain methods or properties will be present on that object. * * @param {Object} prototype an object to be tested against each link in the prototype chain of the * *object* argument * @param {Object} object the object whose prototype chain will be searched * @return {Boolean} Returns true if object is a prototype and false if not. */<span id='Object-method-propertyIsEnumerable'>/**</span> * @method propertyIsEnumerable * Returns a boolean indicating if the internal ECMAScript DontEnum attribute is set. * * Every object has a `propertyIsEnumerable` method. This method can determine whether the specified * property in an object can be enumerated by a `for...in` loop, with the exception of properties * inherited through the prototype chain. If the object does not have the specified property, this * method returns false. * * The following example shows the use of `propertyIsEnumerable` on objects and arrays: * *     var o = {}; *     var a = []; *     o.prop = 'is enumerable'; *     a[0] = 'is enumerable'; * *     o.propertyIsEnumerable('prop');   // returns true *     a.propertyIsEnumerable(0);        // returns true * * The following example demonstrates the enumerability of user-defined versus built-in properties: * *     var a = ['is enumerable']; * *     a.propertyIsEnumerable(0);          // returns true *     a.propertyIsEnumerable('length');   // returns false * *     Math.propertyIsEnumerable('random');   // returns false *     this.propertyIsEnumerable('Math');     // returns false * * Direct versus inherited properties * *     var a = []; *     a.propertyIsEnumerable('constructor');         // returns false * *     function firstConstructor() *     { *         this.property = 'is not enumerable'; *     } *     firstConstructor.prototype.firstMethod = function () {}; * *     function secondConstructor() *     { *         this.method = function method() { return 'is enumerable'; }; *     } * *     secondConstructor.prototype = new firstConstructor; *     secondConstructor.prototype.constructor = secondConstructor; * *     var o = new secondConstructor(); *     o.arbitraryProperty = 'is enumerable'; * *     o.propertyIsEnumerable('arbitraryProperty');   // returns true *     o.propertyIsEnumerable('method');              // returns true *     o.propertyIsEnumerable('property');            // returns false * *     o.property = 'is enumerable'; * *     o.propertyIsEnumerable('property');            // returns true * *     // These return false as they are on the prototype which *     // propertyIsEnumerable does not consider (even though the last two *     // are iteratable with for-in) *     o.propertyIsEnumerable('prototype'); // returns false (as of JS 1.8.1/FF3.6) *     o.propertyIsEnumerable('constructor'); // returns false *     o.propertyIsEnumerable('firstMethod'); // returns false * * @param {String} prop The name of the property to test. * @return {Boolean} If the object does not have the specified property, this * method returns false. */<span id='Object-method-toLocaleString'>/**</span> * @method toLocaleString * Returns a string representing the object. This method is meant to be overridden by derived objects * for locale-specific purposes. * * `Object`'s `toLocaleString` returns the result of calling `toString`. * * This function is provided to give objects a generic `toLocaleString` method, even though not all * may use it. Currently, only `Array`, `Number`, and `Date` override `toLocaleString`. * * @return {String} Object represented as a string. */<span id='Object-method-toString'>/**</span> * @method toString * Returns a string representation of the object. * * Every object has a `toString()` method that is automatically called when the object is to be * represented as a text value or when an object is referred to in a manner in which a string is * expected. By default, the `toString()` method is inherited by every object descended from `Object`. * If this method is not overridden in a custom object, `toString()` returns "[object type]", where * `type` is the object type. The following code illustrates this: * *     var o = new Object(); *     o.toString();           // returns [object Object] * * You can create a function to be called in place of the default `toString()` method. The * `toString()` method takes no arguments and should return a string. The `toString()` method you * create can be any value you want, but it will be most useful if it carries information about the * object. * * The following code defines the `Dog` object type and creates `theDog`, an object of type `Dog`: * *     function Dog(name,breed,color,sex) { *         this.name=name; *         this.breed=breed; *         this.color=color; *         this.sex=sex; *     } * *     theDog = new Dog("Gabby","Lab","chocolate","female"); * * If you call the `toString()` method on this custom object, it returns the default value inherited * from `Object`: * *     theDog.toString(); //returns [object Object] * * The following code creates and assigns `dogToString()` to override the default `toString()` method. * This function generates a string containing the name, breed, color, and sex of the object, in the * form `"property = value;"`. * *     Dog.prototype.toString = function dogToString() { *         var ret = "Dog " + this.name + " is a " + this.sex + " " + this.color + " " + this.breed; *         return ret; *     } * * With the preceding code in place, any time theDog is used in a string context, JavaScript * automatically calls the `dogToString()` function, which returns the following string: * *     Dog Gabby is a female chocolate Lab * * `toString()` can be used with every object and allows you to get its class. To use the * `Object.prototype.toString()` with every object, you need to call `Function.prototype.call()` or * `Function.prototype.apply()` on it, passing the object you want to inspect as the first parameter * called `thisArg`. * *     var toString = Object.prototype.toString; * *     toString.call(new Date); // [object Date] *     toString.call(new String); // [object String] *     toString.call(Math); // [object Math] * * @return {String} Object represented as a string. */<span id='Object-method-valueOf'>/**</span> * @method valueOf * Returns the primitive value of the specified object. * * JavaScript calls the `valueOf` method to convert an object to a primitive value. You rarely need to * invoke the `valueOf` method yourself; JavaScript automatically invokes it when encountering an * object where a primitive value is expected. * * By default, the `valueOf` method is inherited by every object descended from `Object`. Every built- * in core object overrides this method to return an appropriate value. If an object has no primitive * value, `valueOf` returns the object itself, which is displayed as: * *     [object Object] * * You can use `valueOf` within your own code to convert a built-in object into a primitive value. * When you create a custom object, you can override `Object.valueOf` to call a custom method instead * of the default `Object` method. * * You can create a function to be called in place of the default `valueOf` method. Your function must * take no arguments. * * Suppose you have an object type `myNumberType` and you want to create a `valueOf` method for it. * The following code assigns a user-defined function to the object's valueOf method: * *     myNumberType.prototype.valueOf = new Function(functionText) * * With the preceding code in place, any time an object of type `myNumberType` is used in a context * where it is to be represented as a primitive value, JavaScript automatically calls the function * defined in the preceding code. * * An object's `valueOf` method is usually invoked by JavaScript, but you can invoke it yourself as * follows: * *     myNumber.valueOf() * * Note: Objects in string contexts convert via the `toString` method, which is different from * `String` objects converting to string primitives using `valueOf`. All objects have a string * conversion, if only `"[object type]"`. But many objects do not convert to number, boolean, or * function. * * @return {Object} Returns value of the object or the object itself. *///Properties<span id='Object-property-constructor'>/**</span> * @property constructor * Specifies the function that creates an object's prototype. * * Returns a reference to the Object function that created the instance's prototype. Note that the * value of this property is a reference to the function itself, not a string containing the * function's name, but it isn't read only (except for primitive Boolean, Number or String values: 1, * true, "read-only"). * * All objects inherit a `constructor` property from their `prototype`: * *     o = new Object // or o = {} in JavaScript 1.2 *     o.constructor == Object *     a = new Array // or a = [] in JavaScript 1.2 *     a.constructor == Array *     n = new Number(3) *     n.constructor == Number * * Even though you cannot construct most HTML objects, you can do comparisons. For example, * *     document.constructor == Document *     document.form3.constructor == Form * * The following example creates a prototype, `Tree`, and an object of that type, theTree. The example then displays the `constructor` property for the object `theTree`. * *     function Tree(name) { *         this.name = name; *     } *     theTree = new Tree("Redwood"); *     console.log("theTree.constructor is " + theTree.constructor); * * This example displays the following output: * *     theTree.constructor is function Tree(name) { *         this.name = name; *     } * * The following example shows how to modify constructor value of generic objects. Only true, 1 and * "test" variable constructors will not be changed. This example explains that is not always so safe * to believe in constructor function. * *     function Type(){}; *     var	types = [ * 	    new Array,	[], *	    new Boolean,	true, *	    new Date, *	    new Error, *	    new Function,	function(){}, *	    Math, *	    new Number,	1, *	    new Object,	{}, *	    new RegExp,	/(?:)/, *	    new String,	"test" *     ]; *     for(var i = 0; i < types.length; i++){ *         types[i].constructor = Type; *         types[i] = [types[i].constructor, types[i] instanceof Type, types[i].toString()]; *     }; *     alert(types.join("\n")); */</pre></body></html>
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