javascript 新浪背投广告实现代码

新浪的好多广告代码被广大站长广为流传，大家如果有时间可以去看看，他们的代码都是写出类的，不少的好东西。

今天查看了下新浪的js代码，发现一个背投的广告类代码，不论是从学习角度还是使用角度都是不错的，但发现了一个问题，会被屏蔽的。
下面是具体的js类代码

/* 
轮播背投类 RotatorPB v3.1 
Update by Dakular  2008-8-25 
格式：new RotatorPB(广告数组) 
说明：第一次访问随机出现，以后访问顺序轮播；自动过滤过期广告；cookie时间24小时；商业广告数量不足时不显示 
*/ 
if(typeof(RotatorPB)!='function'){ 
    var RotatorPB=function (rad){ 
        this.ary = new Array(); 
        this.date = new Date(); 
        this.w = rad.width; 
        this.h = rad.height; 
        this.num = rad.num; 
        this.o = rad.length; 
        this.id = RotatorPB.id++; 
        this.m = 'rpb_'+this.id; 
        this.n = new Array(); 
        this.L = new Date(); 
        this.e = 0; 
        var f; 
        var D = false; 
        var nn = 0; 
        //过滤无效广告 
        for(var i=0; i            var start = RotatorPB.strToDate(rad[i][2].replace('','').replace('','')); 
            var end = RotatorPB.strToDate(rad[i][3].replace('','').replace('',''),true); 
            if(this.date>start && this.date                this.ary.push([rad[i][0], rad[i][1], rad[i][4]]); 
            } 
        } 
        this.o = this.ary.length; 
        //取id 
        for(var i=0;i            f=this.m+'_'+(i+1); 
            g=RotatorPB.G(f); 
            if(g!=''){ 
                this.n[i]=g; 
                D=true; 
            }else { 
                this.n[i]=0; 
            } 
        } 
        if(!D){ 
            var r=Math.ceil(Math.random()*this.o); 
            var t=this.m+'_'+r; 
            RotatorPB.S(t,this.L.getTime(),1440); 
            this.e=r; 
            if(this.o==1){RotatorPB.S('s_dl',r,1440);} 
            //return r; 
        }else { 
            var R=this.n.join(',').split(','); 
            var k=R.sort(); 
            var max=Number(k[k.length-1]); 
            var min=Number(k[0]); 
            var F; 
            for(var i=0;i                if(max==this.n[i]){ 
                    F=i+1; 
                    break; 
                } 
            } 
            if(typeof(F)!='undefined'){ 
                G=this.m+'_'+F; 
                H=Number(RotatorPB.G(G)); 
                I=F%this.o+1; 
                J=this.m+'_'+I; 
                RotatorPB.S(J,this.L.getTime(),1440); 
                if(this.o==1){ 
                    I=-RotatorPB.G('s_dl'); 
                    if(I==0){I=1;RotatorPB.S('s_dl',1,1440);} 
                    RotatorPB.S('s_dl',I,1440); 
                } 
                this.e=I; 
                //return I; 
            } 
        } 
        //Show AD 
        if(this.e==0 || this.ary.length==0) return; //如果没有广告则不显示 
        if(this.e==-1) return; //当只有一个广告时：始终显示第一个/奇数次刷新显示 
        var n = this.e-1; 
        var btsrc = this.ary[n][0]; 
        var bturl = this.ary[n][1]; 
        var bttype = btsrc.substring(btsrc.length-3).toLowerCase(); 
        if(bttype=='.js'){ //js 
            document.write('