ES6--面向对象

类

ES5通过构造函数生成实例对象

function User(name, pass) {
    this.name = name
    this.pass = pass
}

User.prototype.log = function () {
    console.log('name = ' + this.name + ', pass = ' + this.pass)
}

var user1 = new User('xiaoming', '12356')

user1.log()
//name = xiaoming, pass = 12356

ES6引入class（类）概念与constructor构造方法。定义“类”的方法时，前面不需要加 function 关键字。方法之间不需要逗号分隔，加了会报错。

class User {
    constructor(name, pass) {
        this.name = name
        this.pass = pass
    }

    log() {
        console.log(`name = ${this.name} , pass = ${this.pass}`)
    }
}
let user1 = new User('xiaoming', '12356')
user1.log()
//name = xiaoming , pass = 12356

继承

ES5继承

function VipUser(name, pass, level) {
    User.call(this, name, pass)
    this.level = level
}
VipUser.prototype = new User();
VipUser.prototype.constructor = VipUser
VipUser.prototype.logLevel = function () {
    console.log('level = ' + this.level)
}
var v1 = new VipUser('xiaoming', '123456', '5')
v1.log()
v1.logLevel()

ES6继承（extends和super）

class VipUser extends User {
    constructor(name, pass, level) {
        super(name, pass)
        this.level = level
    }

    logLevel() {
        console.log(`level = ${this.level}`)
    }
}

let v1 = new VipUser('xiaoming', '1234', '5')

 静态方法和静态属性

所有在类中定义的方法，都会被实例继承。如果在一个方法前加上 static 关键字，该方法就不会被实例继承，而是通过类来调用，这种方法或属性被称为静态方法或属性

静态属性的对立面是实例属性（只能通过类的实例来调用）

ES5静态属性与实例属性

function Person(name) {
    this.name = name //实例属性，挂载在实例上
}
//静态属性info，挂载在构造函数（类）上
Person.info = { name: 'zs', age: 20 }

ES6静态属性