可兼容的事件绑定方法

 1 function addEvent(elem,type,handle){
 2     if(elem.addEventListener){
 3          elem.addEventListener(type,handle,false)
 4      }else if(elem.attachEvent){
 5           elem.attachEvent(‘on’+type,function(){
 6                handle.call(div)
 7           })
 8      }else{
 9           elem[‘on’+type] = handle
10      }
11 
12 }