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javascript-关于js的继承方式,求解!

时间:2021-07-01 10:21:17 帮助过:4人阅读

function person(name,age){
    this.name = name;
    this.age = age;
}
person.prototype.say = function(){
    console.log(this.name+":"+this.age);
}

function superman(name,age){
    person.call(this,name,age);
}
superman.prototype = new person();

var s = new superman('superman',29);

在书上看到这种继承方式,说很完美,可是我并不觉得啊,因为他的superman.prototype = new person();这句,会将父类的实例属性添加到子类的原型上啊,虽然person.call(this,name,age);已经拿到了父类的实例属性,但是感觉这样污染了子类的原型啊,怎么破?

好了,问题解决了,使用寄生组合式继承可以解决这个问题

function object(obj){
 function F(){}
 F.prototype = obj;
 return new F();
}

function inheritProtoType(SuperType,SubType){
     var prototype = object(SuperType.prototype);
     prototype.constructor = SubType;
     SubType.prototype = prototype;
}

function SuperType(){
    this.name = 'yuhualingfeng';
    this.friends = ['David','Bob','Lucy'];
}
SuperType.prototype.saySuperName = function(){
    console.log(this.name);
};

function SubType(){
    SuperType.call(this);
    this.age = 30;
}
inheritProtoType(SuperType,SubType);

SubType.prototype.saySubName = function(){
    console.log(this.name);
};

var subType = new SubType();

回复内容:

function person(name,age){
    this.name = name;
    this.age = age;
}
person.prototype.say = function(){
    console.log(this.name+":"+this.age);
}

function superman(name,age){
    person.call(this,name,age);
}
superman.prototype = new person();

var s = new superman('superman',29);

在书上看到这种继承方式,说很完美,可是我并不觉得啊,因为他的superman.prototype = new person();这句,会将父类的实例属性添加到子类的原型上啊,虽然person.call(this,name,age);已经拿到了父类的实例属性,但是感觉这样污染了子类的原型啊,怎么破?

好了,问题解决了,使用寄生组合式继承可以解决这个问题

function object(obj){
 function F(){}
 F.prototype = obj;
 return new F();
}

function inheritProtoType(SuperType,SubType){
     var prototype = object(SuperType.prototype);
     prototype.constructor = SubType;
     SubType.prototype = prototype;
}

function SuperType(){
    this.name = 'yuhualingfeng';
    this.friends = ['David','Bob','Lucy'];
}
SuperType.prototype.saySuperName = function(){
    console.log(this.name);
};

function SubType(){
    SuperType.call(this);
    this.age = 30;
}
inheritProtoType(SuperType,SubType);

SubType.prototype.saySubName = function(){
    console.log(this.name);
};

var subType = new SubType();

Object.create(Person.prototype);

这个可以有效解决,不过要注意兼容性

function create(obj) {
    if (Object.create) {
        return Object.create(obj);
    }

    function f() {};
    f.prototype = obj;
    return new f();
}

继承 person.prototype

继承而不是污染

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