function Animation(list) {

    this.box = document.getElementById(list.id);

    this.size = list.size;

    this.url = list.url;

    this.init()            //    Animation.prototype中的init()，初始化一些值(非私有)

    this.DOMready();    //    调用Animation.prototype中的 DOMready()，每一个new Animation()都会执行这里面的语句

}

Animation.prototype = {

    //    1.init:初始化一些非私有值

    init:function(){

        this.width  = box.clientWidth;

        this.height = box.clientHeight;

    },

   //    2.DOMready:用来生成div的,用到定时器,循环设置

    DOMready: function(){

        var box = this.box;

        var size = this.size;

        // 下面保存了this(Animation)到self之中,因为等会要调用Animation.DOMmove(cirDiv)

        var self = this;

        var timer = setInterval(function(){

            var top = ;

            var xPosition = Math.random()*(self.width - self.size);

            var cirDiv = document.createElement("div");

            cirDiv.style.cssText = "background:"+LYX_Colors_getRandomColor()+";"+"left:"+xPosition+"px;"+ "width:25px;height:25px;border-radius: 50%;position: absolute;";

            box.appendChild(cirDiv);

            //    调用Animation.DOMmove(cirDiv),给每个div设置定时器,用来调整top值

            self.DOMmove(cirDiv)

        }, )

    },

    //    3.调整top值函数

    DOMmove: function(cirDiv) {

        var top = ;

        var self = this;

        var cirDiv = cirDiv;

        var timer_2 = setInterval(function() {

            top++;

            cirDiv.style.top = top+"px";

            if (top > self.height - self.size) {

                box.removeChild(cirDiv);

                clearInterval(timer_2);

            }

        },)

    }

}

//    新建s调用方法

var s = new Animation({

    id: "box",

    size: ""

});