网站中4个标签轮流显示问题！！

var currentTag = 1;
function fivetag(obj,id){
selectMenu(obj);
for (var i =1,j; j=document.getElementById("tag_content_"+i); i++){
j.style.display="none";
}
document.getElementById("tag_content_"+id).style.display="block";
currentTag++;
if (currentTag>4)
//currentTag=1;
break;
}
function selectMenu(obj){
var lia = document.getElementById("menulist").getElementsByTagName("li");
var lialen = lia.length;
for(i=0; iif(lia[i].getElementsByTagName("a")[0].className=="curMenu")
lia[i].getElementsByTagName("a")[0].className = "";
}
obj.className = "curMenu";
}
function init(){
var menulist = document.getElementById("menulist");
setInterval('fivetag(menulist.getElementsByTagName("li")[currentTag-1].getElementsByTagName("a")[0],currentTag)',3000);
}