复制代码 代码如下:
<script>
//定义js的user对象
function User(name,age){
this.name=name,
this.age=age,
this.getName=function(){
return this.name;
},
this.getAge=function(){
return this.age;
}
}
//实例化一个对象
var use=new User("aa",21);
alert(use.name);
alert(use.getAge());
//js对象继承

function Polygon(iSides){
this.sides = iSides;
}
Polygon.prototype.getAreas = function(){
return 0;
}

function Triangle(iBase, iHeight){
Polygon.call(this,3); //在这里我们用Polygon.call()来调用Polygon的构造函数，并将3作为参数，表示这是一个三角形，因为边是确定的，所以在子类的构造函数中就不需要指定边了
this.base = iBase; //三角形的底
this.height = iHeight; //三角形的高
}
Triangle.prototype = new Polygon();
Triangle.prototype.getAreas = function(){
return 0.5 * this.base *this.height; //覆盖基类的getAreas方法，返回三角形的面积
}


function Rectangle(iWidth, iHeight){
Polygon.call(this,4);
this.width = iWidth;
this.height = iHeight;
}
Rectangle.prototype = new Polygon();
Rectangle.prototype.getAreas = function(){
return this.width * this.height;
}

var t = new Triangle(3,6);
var r = new Rectangle(4,5);
alert(t.getAreas()); //输出9说明正确
alert(r.getAreas()); //输出20说明正确
</script>