ES6 class的应用实例分析

本文实例讲述了ES6class的应用。分享给大家供大家参考，具体如下：classclass本身是个语法糖

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;
 }
}