JavaScript Objects have properties, which are composed by a label associated with a value.The object literal syntax we saw:const car = { }lets us define properties like this:const car = { color: 'blue' }here we have a car object with a property named color, with value blue....
Iterating the obejct properties color: brown shape: round price: 10000 Property Attributes The object property contains four attributes. value− A value of the object. enumerable− Contains boolean value representing whether the object is iterable. ...
You can add new properties to an existing object by simply giving it a value: Example person.nationality="English"; Try it Yourself » Deleting Properties Thedeletekeyword deletes a property from an object: Example constperson = { firstName:"John", ...
Object.defineProperty(person,'name',{ configurable:true,//能否使用delete、能否修改属性特性、或能否修改访问器属性、,false为不可重新定义,默认值为trueenumerable:false,//对象属性是否可通过for-in循环,flase为不可循环,默认值为true//writable:true,//对象属性是否可修改,flase为不可修改,默认值为true//value:...
Internal properties have special names that are written in double square brackets. Two examples: The internal property [[Prototype]] points to the prototype of an object. It can be read via Object.getPrototypeOf(). Its value can only be set by creating a new object that has a given ...
Object.defineProperty(obj,"subtract", { set :function(i) {this.counter-= i;} }); // Play with the counter: obj.reset; obj.add=5; obj.subtract=1; obj.increment; obj.decrement; Try it Yourself » Prototype Properties JavaScript objects inherit the properties of their prototype. ...
Object.defineProperties()方法直接在一个对象上定义新的属性或修改现有属性,并返回该对象。 语法 Object.defineProperties(obj, props) 参数 obj 在其上定义或修改属性的对象。 props 要定义其可枚举属性或修改的属性描述符的对象。对象中存在的属性描述符主要有两种:数据描述符和访问器描述符(更多详情,请参阅Object...
The Object object inherits from the Function.prototype object and the Function.prototype object inherits from the Object.prototype object. The Object.prototype object is the base object for all JavaScript objects. The Object object inherits all of its properties and methods from the Function.prototype...
Other read operations only work with own properties: > Object.getOwnPropertyNames(obj) [ 'baz', 'qux' ] > obj.hasOwnProperty("qux") true > obj.hasOwnProperty("toString") false > Object.getOwnPropertyDescriptor(obj, "qux") { value: 2, ...
Example 2: defineProperties() With Data Descriptors let obj = {}; // define the object's properties using // data descriptors value and writable Object.defineProperties(obj, { "id": { value: 711, writable: false }, "email": { value: "[email protected]", writable: true } }); ...