This article briefly introduces the usage and benefits of JavaScript event delegation for your reference. The specific content is as follows
Event delegation: Using the principle of bubbling, add events to the parent to trigger execution effects,
Benefits: Improved performance, newly added elements will also have previous events.
event object: event source, no matter which event it is in, as long as the element you operate is the event source
Get event source:
IE：window.event.srcElement
Under the standard : event.target target.nodeName to determine which tag
The code is applied as follows:
<!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>
<style>
</style>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<script type="text/javascript">
window.onload=function ()
{
var oUl=document.getElementById('ul1');
var oBtn=document.getElementById('btn1');
var iNow=5;
//事件源的方法依然保留父级事件！
oUl.onmouseover=function(ev)
{
var ev=ev||window.event;
var target=ev.target||ev.srcElement;
if(target.nodeName.toLowerCase()=='li')
{
target.style.background='red';
}
}
oUl.onmouseout=function(ev)
{
var ev=ev||window.event;
var target=ev.target||ev.srcElement;
if(target.nodeName.toLowerCase()=='li')
{
target.style.background='';
}
}
oBtn.onclick=function()
{
iNow++;
var oLi=document.createElement('li');
oLi.innerHTML=111*iNow;
oUl.appendChild(oLi);
}
}
</script>
</head>
<body >
<input type="button" value="添加" id='btn1'>
<ul id='ul1'>
<li>11111</li>
<li>22222</li>
<li>3333333</li>
<li>44444444</li>
<li>66666666</li>
</ul>
</body>
</html>
The above is the entire content of this article, I hope it will be helpful to everyone’s study.
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