JavaScript 继承，看过来

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这是一个创建于 2054 天前的主题，其中的信息可能已经有所发展或是发生改变。

JavaScript 有多种方式实现继承，下面这些大家哪种用的比较多，还有没有其它方式？

ES6 引入的 class 是不是最佳实践呢？ ES5 时代，大家都用什么方式？

组合 /模块模式的方式是不是可以作为继承的替代？

请大家指导，各抒己见。

构造函数

function SuperClass(p) {
    this.prop = p
    this.method = function () {return this.prop}
}

function SubClass(p2) {
    this.prop2 = p2
    this.method2 = function () {return this.prop2}
}

SubClass.prototype = new SuperClass('prop') // inherit/extends

let so = new SubClass('prop2') // create instance

console.log(so.method())
console.log(so.method2())

Object.create

let SuperObject = {
    prop: 'prop',
    method: function () {
        return this.prop
    }
}

let SubObject = Object.create(SuperObject) // equals to inheritance/extension

let so = Object.assign(SubObject, { // equals to instantiation
    prop2: 'prop2',
    method2: function () {
        return this.prop2
    }
})

console.log(so.method())
console.log(so.method2())

Object.setPrototypeOf

let SuperObject = {
    prop: 'prop',
    method: function () {
        return this.prop
    }
}

let SubObject = {
    prop2: 'prop2',
    method2: function () {
        return this.prop2
    }
}

let so = Object.setPrototypeOf(SubObject, SuperObject) // equals to inheritance/extension, and  equals to instantiation also

console.log(so.method())
console.log(so.method2())

Class

class SuperClass {
    constructor(p) {
        this.prop = p
    }

    method() {
        return this.prop
    }
}

class SubClass extends SuperClass { // inherit/extends
    constructor(p2) {
        super('prop')
        this.prop2 = p2
    }

    method2() {
        return this.prop2
    }
}

let so = new SubClass('prop2') // create instance

console.log(so.method())
console.log(so.method2())

组合或模块模式

let SuperClass = {
    createNew: function (p) {
        let prop = p
        let o = {}
        o.method = function () {
            return prop
        }
        return o
    }
}

let SubClass = {
    createNew: function (p2) {
        let prop2 = p2
        let o = SuperClass.createNew('prop') // equals to inheritance/extension, you can use composition also
        o.method2 = function () {
            return prop2
        }
        return o
    }
}

let so = SubClass.createNew('prop2') // equals to instantiation

console.log(so.method())
console.log(so.method2())

6 条回复 • 2019-04-08 18:54:41 +08:00