JS中prototype关键字的功能介绍及使用示例

(编辑：jimmy 日期: 2025/9/16 浏览：2)

prototype 关键字可以为 JS原有对象或者自己创建的类中添加方法或者属性。
也可以实现继承。
例子：
复制代码代码如下:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JS中 prototype 关键字的使用</title>
</head>
<script>

Number.prototype.add = function (num){
return this+num;
}
function but1_click(){
alert((3).add(8));
}

function Car(cColor,cWeight){
this.cColor = cColor;
this.cWeight = cWeight;
}
Car.prototype.drivers = new Array('zhangsan','lisi');
Car.prototype.work = function (cLong){
alert("我跑了"+cLong+"公里");
}
function but2_click(){
var c = new Car("red","5");
c.drivers.push('zhaoliu');
alert(c.drivers);
c.work(1);
}

function Rectangle(rWeight,rHeight){
this.rWeight = rWeight;
this.rHeight = rHeight;
if( typeof this._init == 'undefined'){
Rectangle.prototype.test = function (){
alert("test");
}
}
this._init = true;
}
function but3_click(){
var t = new Rectangle(6,8);
t.test();
}

function objectA(){
this.methodA = function (){
alert("我是A方法");
}
}
function objectB(){
this.methodB = function (){
alert("我是B方法");
}
}
objectB.prototype = new objectA();
function but4_click(){
var t = new objectB();
t.methodB();
t.methodA();
}
</script>
<body>
<h2> prototype 关键字的使用 </h2>
<hr />
<input id="but1" type="button" value="demo1" onclick="but1_click()" />
<input id="but2" type="button" value="demo2" onclick="but2_click()" />
<input id="but3" type="button" value="demo3" onclick="but3_click()" />
<input id="but4" type="button" value="demo4" onclick="but4_click()" />
</body>
</html>

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