js 根据cookie判断该页面浏览次数

<script type="text/javascript"> 
if(getCookie("num")){ 
var nn=parseInt(getCookie("num")); 
setCookie("num",++nn); 
}else{ 
setCookie("num",1); 
} 
function getCookie(name){ 
var str=document.cookie.split(";"); 
for(i=0;i<str.length;i++){ 
var str2=str[i].split("=") 
if(str2[0].replace(/s(.*)s/,"$1")==name){ 
return str2[1]; 
} 
} 
} 
function setCookie(name,value){ 
var Days=30; 
var exp = new Date(); 
exp.setTime(exp.getTime() + Days*24*60*60*1000); 
document.cookie = name + "="+ escape(value) +";expires"+ exp.toGMTString(); 
} 
alert("您是第"+getCookie("num")+"次访问"); 
/*String.prototype.Trim=function(){ 
return this.replace(/s(.*)s/,"$1"); 
} 
String.prototype.alert2=function(str){ 
alert("我是alert2！！！哈哈哈哈 实际内容是:"+str); 
} 
var aa=""; 
aa.alert("liugang");*/ 
</script>