js中面向对象的5钟写法(转)

//第1种写法
function Circle(r) {
    //对象属性
    this.R = r;
}
//对象静态属性
Circle.PI = 3.1415926;
//对象静态方法
Circle.prototype.area = function () {
    return Circle.PI * this.R * this.R
};

var c = new Circle(1.0);
alert(c.area());

//第2种写法
var Circle = function () {
    var obj = new Object();
    //对象属性
    obj.PI = 3.1415926;
    //对象方法
    obj.area = function (r) {
        return this.PI * r * r
    }
    return obj;
}
var c = new Circle();
alert(c.area(1.0));

//第3种写法
var Circle = new Object();
//对象静态属性
Circle.PI = 3.1415926;
//对象静态方法
Circle.Area = function (r) {
    return this.PI * r * r;
};

alert(Circle.Area(1.0));

//第4种写法
var Circle = {
    //对象静态属性
    "PI": 3.1415926,
    //对象静态方法
    "area": function (r) {
        return this.PI * r * r;
    }
};

alert(Circle.area(1.0));

//第5种写法
var Circle = new Function("this.PI = 3.14159;this.area = function( r ) {return r*r*this.PI;}");

alert(new Circle().area(1.0));

转自：http://www.cnblogs.com/GIS_zhou/archive/2009/07/29/1534491.html