//添加事件监听兼容函数

 function addHandler(target, eventType, handler){

     if(target.addEventListener){//主流浏览器

         addHandler = function(target, eventType, handler){

             target.addEventListener(eventType, handler, false);

         };

     }else{//IE

         addHandler = function(target, eventType, handler){

             target.attachEvent("on"+eventType, handler);

         };

     }

     //执行新的函数

     addHandler(target, eventType, handler);

 }

 //删除事件监听兼容函数

 function removeHandler(target, eventType, handler){

     if(target.removeEventListener){//主流浏览器

         removeHandler = function(target, eventType, handler){

             target.removeEventListener(eventType, handler, false);

         }

     }else{//IE

         removeHandler = function(target, eventType, handler){

             target.detachEvent("on"+eventType, handler);

         }

     }

     //执行新的函数

     removeHandler(target, eventType, handler);

 }