js 4种方式实现继承.
2011-11-22 16:05
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<script type="text/javascript"><!--
//冒充对象
/*function Parent(username)
{
this.username=username;
this.sayHello=function()
{
alert(this.username);
}
}
function Child(username,password)
{
this.method=Parent;
this.method(username);
delete this.method;
this.password=password;
this.sayWorld=function()
{
alert(this.password);
}
}
var parent=new Parent("zhangsan");
var child=new Child("lisi","1234");
parent.sayHello();
child.sayHello();
child.sayWorld();
*/
//call 方式实现对象的继承
/*
function Parent(username)
{
this.username=username;
this.sayHello=function()
{
alert(this.username);
}
}
function Child(username,password)
{
Parent.call(this,username);
this.password=password;
this.sayWorld=function()
{
alert(this.password);
}
}
var parent=new Parent("zhangsan");
var child=new Child("lisi","1234");
parent.sayHello();
child.sayHello();
child.sayWorld();
*/
//apply 方式实现对象的继承
/*function Parent(username)
{
this.username=username;
this.sayHello=function()
{
alert(this.username);
}
}
function Child(username,password)
{
Parent.apply(this,new Array(username));
this.password=password;
this.sayWorld=function()
{
alert(this.password);
}
}
var parent=new Parent("zhangsan");
var child=new Child("lisi","1234");
parent.sayHello();
child.sayHello();
child.sayWorld();
*/
//prototype chain
/*
function Parent()
{}
Parent.prototype.name="zhangsan";
Parent.prototype.sayHello=function()
{
alert(this.name);
}
function Child()
{}
Child.prototype=new Parent();
Child.prototype.world="world";
Child.prototype.sayWorld=function()
{
alert(this.world);
}
var child=new Child();
child.sayHello();
child.sayWorld();
*/
//混合方式实现对象的继承(推荐)
function Parent(name)
{
this.name=name;
}
Parent.prototype.sayHello=function()
{
alert(this.name);
}
function Child(name,world)
{
Parent.call(this,name);
this.world=world;
}
Child.prototype=new Parent();
Child.prototype.sayWorld=function()
{
alert(this.world);
}
var child=new Child("name","world");
child.sayHello();
child.sayWorld();
</script>
<body>
</body>
</html>
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