为什么不能阻止冒泡和默认行为
// JavaScript Document
//这是event.js
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.attachEvent)
{
element.detachEvent('on'+type,handler);
}
else{
element['on'+type]=null;
}
},
//获取事件对象
getEvent:function(event)
{
return event?event:window.event;
},
//获取事件类型
getType:function(event)
{
return event.type;
},
//获取事件节点
getElement:function(event)
{
return event.target.nodeName||event.srcElement;
},
//阻止事件的默认行为
preventDefault:function(event)
{
if(event.preventDefault)//判断时方法不加括号
{
event.preventDefault();
}
else
{
event.returnValue=false;
}
},
//阻止冒泡
stopPropagation:function(event)
{
if(event.stopPropagation)
{
event.stopPropagation();
}
else
{
event.cancelBubble=true;
}
},
}//这是script.js
// JavaScript Document
window.onload=function()
{
var go=document.getElementById('go');
var box=document.getElementById('box');
eventUtil.addHandler(box,'click',function()
{
alert('我是盒子box!');
});
eventUtil.addHander(go,'click',function(e)
{e=eventUtil.getEvent(e);
alert(eventUtil.getElement(e));
eventUtil.preventDefault(e);
eventUtil.stopPropagation(e);
});
}
这是HTML<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>事件处理程序</title> <script src="event.js"></script> <script src="script.js"></script> </head> <body> <div id="box"> <input type="button" id="btn" value="按钮" onclick="showMes()"/> <input type="button" id="btn2" value="按钮2" /> <input type="button" id="btn3" value="按钮3" /> <a href="HelloWorld.html" id="go">跳转</a> </div> </body> </html>
为什么不能阻止冒泡和默认行为？？求解
运行 效果是
这是我dw，index是HTML文件
