javascript继承方式

1. 使用for-in实现继承
2. 通过call或者apply实现伪造继承
3. 通过原型对象实现继承
4. 通过原型和call的组合实现继承

    //1、使用for-in实现继承
    function Parent() {
        this.name = 'parent';
        this.color = ['red', 'green'];
    }
    Parent.prototype.showName = function () {
        return `姓名：${this.name}`;
    }
    function Child(age) {
        this.age = age ;
        let p = new Parent();
        for(let key in p) {
            this[key] = p[key];
        }
    }
    Child.prototype.getAge = function () {
        return `芳龄：${this.age}`;
    }

    let child = new Child(18);
    child.name = 'Child';
    console.log(child);
    console.log(child.getAge());
    console.log(child.showName());

    //2、通过call或者apply实现伪造继承
    function Parent2(name, email) {
        this.name = name;
        this.email = email;
        this.sayHi = function () {
            return 'hhh';
        }
    }
    // 使用call或apply不可以实现原型对象上面的属性和方法的继承
    Parent2.prototype.say = function () {
        return 'hello';
    }
    function Child1(name, age, email) {
        this.age = age;
        Parent2.call(this, name, email);
    }
    function Child2(name, email) {
        this.age = 22;
        // arguments是函数内部获取实参的集合
        Parent2.apply(this,arguments);
    }

    let child1 = new Child1('zs',33,'[email protected]');
    let child2 = new Child2('zs','[email protected]');
    console.log(child1);

    //3、通过原型对象实现继承
    function Parent3() {
        this.name = 'parent';
        this.color = ['red', 'green'];
    }
    Parent3.prototype.showName = function () {
        return `parent：my name is ${this.name}`;
    }
    function Child3(age) {
        this.age = age ;
    }
    Child3.prototype = new Parent3();
    Child3.prototype.getAge = function () {
        return `child：my age is ${this.age}`;
    }

    let child3 = new Child3(12);
    console.log(child3.showName());
    console.log(child3.getAge());

    //4、通过原型和call的组合实现继承
    function Parent4(name, color) {
        this.name = name;
        this.color = color;
    }
    Parent4.prototype.showName = function () {
        return `parent4: ${this.name}`;
    }
    function Child4(age, name, color) {
        this.age = age;
        Parent4.call(this,name,color);
    }
    Child4.prototype = new Parent4('parent4',['yellow']);
    Child4.prototype.getAge = function () {
        return `child4：my age is ${this.age}`;
    }

    let child4 = new Child4(25,'k',['k_color']);
    console.log(child4.name);
    console.log(child4.getAge());
    child4.color.push('k1_color');
    console.log(child4.color);

    let child5 = new Child4(26,'k5',['k5_color']);
    child5.color.push('k55_color');
    console.log(child4.color);
    console.log(child5.color);