js的三种继承方式详解

时间：2021-05-26

1.js原型（prototype）实现继承

代码如下

<body> <script type="text/javascript"> function Parent(name,age){ this.name=name; this.age=age; this.sayHi=function(){ alert("Hi, my name is "+this.name+", my age is "+this.age); } }//Child继承Parent function Child(grade){ this.grade=grade; this.sayGrade=function(){ alert("My grade is "+this.grade); } } Child.prototype=new Parent("小明","10");/////////// var chi=new Child("5"); chi.sayHi(); chi.sayGrade();</script> </body>

2.构造函数实现继承

代码如下:

<body> <script type="text/javascript"> function Parent(name,age){ this.name=name; this.age=age; this.sayHi=function(){ alert("Hi, my name is "+this.name+", my age is "+this.age); } }//Child继承Parent function Child(name,age,grade){ this.grade=grade; this.sayHi=Parent;/////////// this.sayHi(name,age); this.sayGrade=function(){ alert("My grade is "+this.grade); } } var chi=new Child("小明","10","5"); chi.sayHi(); chi.sayGrade();</script> </body>

3.call , apply实现继承 -----很方便！

代码如下:

<body> <script type="text/javascript"> function Parent(name,age){ this.name=name; this.age=age; this.sayHi=function(){ alert("Hi, my name is "+this.name+", my age is "+this.age); } } function Child(name,age,grade){ this.grade=grade; // Parent.call(this,name,age);/////////// // Parent.apply(this,[name,age]);/////////// 都可 Parent.apply(this,arguments);/////////// this.sayGrade=function(){ alert("My grade is "+this.grade); } // this.sayHi=function(){ // alert("Hi, my name is "+this.name+", my age is "+this.age+",My grade is "+this.grade); // } } var chi=new Child("小明","10","5"); chi.sayHi(); chi.sayGrade();</script> </body>

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