function g(o){return document.getElementById(o);}
if (document.attachEvent){
addEvent = function(o,evn,f){o.attachEvent("on"+evn,f)}
}
else if (document.addEventListener){
addEvent = function(o,evn,f){o.addEventListener(evn,f,false)}
}
/**
* 功能：选项卡
* @param {String} nid 导航栏容器的id，导航栏里必须是li，至于是ul还是li就看个人喜好了
* @param {String} cid 内容容器的id，内容容器里的第一层子节点（排除文本节点）都将作为内容处理
* @param {String} action 操作，单击或鼠标移动
* @param {integer} defaultIndex 默认选中第几个选项卡，如果数字非法或者未提供数字则默认第一个
* @exception 当导航栏和内容数量不对应时抛出错误
* @author Sheneyan
*/
function initTab(nid,cid,action,defaultIndex){
var ls = g(nid).getElementsByTagName('li');
var cc = g(cid).childNodes;
var c = [];
var index = defaultIndex?defaultIndex:0;
for (var i = 0 ; i < cc.length ; i ++)if(cc[i].nodeType==1)c.push(cc[i]);
if (ls.length!=c.length)
   throw({description:'菜单和内容数量不对应'});
for (var i = 0 ; i < ls.length ; i ++){
   ls[i].index = i;
   if (i==index){
     ls[i].className = 'hovertab';
     c[i].className = 'dis'
     ls[i].parentNode.last = ls[i];
   }
   addEvent(ls[i],action,function(e){
     var self = window.event?window.event.srcElement:e?e.target:null;
     if (self.parentNode.last){
       self.parentNode.last.className = 'normaltab';
       c[self.parentNode.last.index].className = 'undis';
     };
     self.className = 'hovertab';
     c[self.index].className = 'dis';
     self.parentNode.last = self;
   });
}
}