ES6 class的应用实例分析
Johnny丶me 人气:0本文实例讲述了ES6 class的应用。分享给大家供大家参考,具体如下:
class
- class 本身是个语法糖,主要为了考虑在编码上更加人性化
- 内部有super,static,get 等关键词
- 使用起来非常类似于后台语言
使用class进行类的实现应用
'use strict'; // User 类 class User { constructor(name,age) { this.name = name; this.age = age; } static getName() { return 'User'; } static getAge() { return this.age; } setName(name) { this.name = name; } setAge(age) { this.age = age; } get info() { return 'name:' + this.name + ' | age:' + this.age; } } // Manager 类 class Manager extends User{ constructor(name,age,password){ super(name,age); this.password = this.password; } changePwd(pwd) { return this.password = pwd; } get info() { var info = super.info; // 使用super继承父级 get return info + ' === new'; } } // typeof User: function typeof Manager: function console.log('typeof User: ', typeof User, ' typeof Manager: ', typeof Manager); let manager = new Manager('Li', 22, '123456'); manager.setAge(23); console.log(manager.info); // name:Li | age:23 === new console.log(User.prototype); console.log(Manager.prototype);
在class之前使用原型对象定义类的应用
// 构造函数 function User(name,age) { this.name = name; this.age = age; } // 原型 User.prototype = { getName:function(){ return 'User'; }, setName:function(name){ this.name = name; }, getAge:function(){ return this.age; }, setAge:function(age){ this.age = age; } } // 取值函数和存执函数 Object.defineProperty(User.prototype,'info', { get() { return 'name:' + this.name + ' | age:' + this.age; } }); var user = new User('Joh', 26); console.log(user); // User {name: "Joh", age: 26} // 子类 function Manager(name, age, password) { User.call(this, name, age); this.password = password; } Manager.__proto__ = User; // 继承静态方法 Manager.prototype = Object.create(User.prototype); // 继承prototype原型方法 Manager.prototype.changePwd = function (pwd) { this.password = pwd; }; var manager = new Manager('Li', 22, '123456'); manager.setAge(23); console.log(manager.info); // name:Li | age:23 console.log(User.prototype); // 不变 console.log(Manager.prototype); // {changePwd:function(){}, info:"name:undefined | age:undefined", __proto__:指向Manager.prototype}
使用 class 定义的类不被提升,需按顺序执行
正常:
let user = new class User { constructor(name) { this.name = name; } }('Joh'); console.log(user); // User {name: "Joh"}
错误:
var man = new Man(); // 此处报错,使用class声明的类不会被提升 Uncaught ReferenceError: Man is not defined class Man { constructor(name){ this.name = name; } }
希望本文所述对大家JavaScript程序设计有所帮助。
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