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js的三种继承方式详解

2017-01-21 08:22 726 查看

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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标签： js 继承方式

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