Object.create(proto, [propertiesObject ]) 是ES5中提出的一种新的对象创建方式,第一个参数是要继承的原型,如果不是一个子函数,可以传一个null,第二个propertiesObject参数是属性描述符,只能传 null 或一个对象,否则抛出一个 TypeError 异常。举个栗子: let obj=Object.create(null,{ name:{ value:"pingfan",...
Use the Object.keys() method, passing the object you want to inspect, to get an array of all the (own) enumerable properties of the object.Then calculate the length of that array by checking the length property:const car = { color: 'Blue', brand: 'Ford', model: 'Fiesta' } Object....
Object.defineProperty() / Object.defineProperties() 新增/修改属性 obj prop / props 属性描述符 configurable 可改可删 默认false enumerable 可枚举属性 默认false value writable get set Object.getOwnPropertyDescriptor(obj, prop) 获取属性描述符对象 Object.getOwnPropertyDescriptors() 获取所有属性的 复制对象...
Object.defineProperties: varp={}; Object.defineProperties(p, { sex: { value:'boy', writable:true, enumerable:false, configurable:false}, age2: {set: function(x) {this.age2Value =x; },get: function() {returnthis.age2Value; } } }); console.dir(p);vardesc=Object.getOwnPropertyDescri...
Object.getOwnPropertyNames(object) List all Object Properties This example gets all properties of an object: Example // Create an Object constperson = { firstName:"John", lastName :"Doe", language :"EN" }; // Get all Properties Object.getOwnPropertyNames(person); ...
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. ...
1functionMyObject() {}2varobj =newMyObject();3console.log(Object.prototype.isPrototypeOf(obj)); 我们知道MyObject是继承自Object对象的,而在JS中,继承是通过prototype来实现的,所以Object的prototype必定在MyObject对象实例的原型链上。 propertyIsEnumerable(prototypeName)方法 ...
Object.assign() Object.create() Object.defineProperty() 属性描述符 描述符默认值汇总 描述符可拥有的键值 创建属性 修改属性 Writable 属性 Enumerable 属性 Configurable 属性 添加多个属性和默认值 自定义 Setters 和 Getters 继承属性 Object.defineProperties() Object.entries() Object.freeze() Object.getOwnP...
Deleting Properties Thedeletekeyword deletes a property from an object: Example constperson = { firstName:"John", lastName:"Doe", age:50, eyeColor:"blue" }; deleteperson.age; Try it Yourself » or delete person["age"]; Example
> Object.getOwnPropertyDescriptor(obj, "toString") undefined Creating, deleting and defining properties only affects the first object in a prototype chain: obj.propName = value obj["propName"] = value delete obj.propName delete obj["propName"] ...