// 事件处理对象

var EventUtil = {

 // 添加事件监听

 add: function(element, type, callback){

  if(element.addEventListener){

   element.addEventListener(type, callback, false);

  } else if(element.attachEvent){

   element.attachEvent('on' + type, callback);

  } else {

   element['on' + type] = callback;

  }

 },

 // 移除事件监听

 remove: function(element, type, callback){

  if(element.removeEventListener){

   element.removeEventListener(type, callback, false);

  } else if(element.detachEvent){

   element.detachEvent('on' + type, callback);

  } else {

   element['on' + type] = null;

  }

 },

 // 跨浏览器获取 event 对象

 getEvent: function(event){

  return event ? event : window.event;

 },

 // 跨浏览器获取 target 属性

 getTarget: function(event){

  return event.target || event.srcElement;

 },

 // 阻止事件的默认行为

 preventDefault: function(event){

  if(event.preventDefault){

   event.preventDefault();

  } else {

   event.returnValue = false;

  }

 },

 // 阻止事件流或使用 cancelBubble

 stopPropagation: function(){

  if(event.stopPropagation){

   event.stopPropagation();

  } else {

   event.cancelBubble = true;

  }

 }

};