js事件 封装方法（添加事件、删除事件、阻止冒泡、阻止默认行为）

var eventUtil={            // 添加句柄            addHandler:function(element,type,handler){               if(element.addEventListener){                 element.addEventListener(type,handler,false);               }else if(element.attachEvent){                 element.attachEvent('on'+type,handler);               }else{                 element['on'+type]=handler;               }            },            // 删除句柄            removeHandler:function(element,type,handler){               if(element.removeEventListener){                 element.removeEventListener(type,handler,false);               }else if(element.detachEvent){                 element.detachEvent('on'+type,handler);               }else{                 element['on'+type]=null;               }            },          getEvent:function(event){            return event?event:window.event;          },          getType:function(event){            return event.type;          },          getElement:function(event){            return event.target || event.srcElement;          },          preventDefault:function(event){            if(event.preventDefault){              event.preventDefault();            }else{              event.returnValue=false;            }          },         stopPropagation:function(event){           if(event.stopPropagation){             event.stopPropagation();           }else{             event.cancelBubble=true;           }         }  }