事件委托
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" >
<title></title>
</head>
<body>
<ul id="myLinks">
<li id="goSomewhere">Go somewhere</li>
<li id="doSomething">Do something</li>
<li id="sayHi">Say hi</li>
</ul>
<script type="text/javascript">
window.onload= function() {
var list = document.getElementById("myLinks");
addHandler(list, "click", function(ev) {
var oEvent = ev||event;
var target = getTarget(oEvent);
switch(target.id) {
case "doSomething":
document.title = "I changed the document's title";
break;
case "goSomewhere":
location.href = "http://www.baidu.com";
break;
case "sayHi":
alert("hi");
break;
}
})
}
function getTarget(event)
{
return event.target || event.srcElement;
}
function addHandler(element, type, handler)
{
if(element.addEventListener)
{
element.addEventListener(type, handler, false);//IE9、ff、sa、op、ch
}else if (element.attachEvent)
{
element.attachEvent("on" + type, handler);//IE、op
}else
{
element["on" + type] = handle;
}
}
</script>
</body>
</html>
事件委托的优点：只为<ul>元素添加事件处理程序，列表项为子节点，事件会冒泡，事件处理程序会执行，至取得了一个DOM元素，只添加了一个事件处理函数，结果相同但所占用的内存更少。
