js事件委托实例
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style type="text/css">
html,body{
min-height: 100%;
}
*{
margin:0;
padding:0;
}
li{
list-style: none;
}
.menuBox{
width:700px;
margin: 20px auto;
height:270px;
border:1px solid #000;
}
.navBox{
float: left;
width: 198px;
background: #FF0;
}
.navBox ul li{
height:30px;
line-height: 30px;
}
.navBox ul li a{
padding:0 10px;
display: block;
height:100%;
font-size: 14px;
color:#555;
text-decoration: none;
}
.navBox ul li a:hover{
background: lightcoral;
}
.detailsBox{
float:left;
width: 500px;
height: 100%;
background:#EEE;
display: none;
}
</style>
</head>
<body>
<section class='menuBox'>
<nav class="navBox">
<ul>
<li><a href="#" target="_blank">导航1</a></li>
<li><a href="#" target="_blank">导航2</a></li>
<li><a href="#" target="_blank">导航3</a></li>
<li><a href="#" target="_blank">导航4</a></li>
<li><a href="#" target="_blank">导航5</a></li>
<li><a href="#" target="_blank">导航6</a></li>
<li><a href="#" target="_blank">导航7</a></li>
<li><a href="#" target="_blank">导航8</a></li>
<li><a href="#" target="_blank">导航9</a></li>
</ul>
</nav>
<div class="detailsBox">导航一对应得详情内容</div>
</section>
<script src='./js/jquery.min.js'></script>
<script type="text/javascript">
//=>基于事件委托给最外层得盒子MOUSE-OVER绑定方法，这样不管操作后代元素中得谁得MOUSE-OVER，这个方法都会执行,
let $detailsBox = $('.detailsBox');
$(document.body).on('mouseover',function(ev){
// console.log(ev)
var target = ev.target || ev.srcElement,
tag = target.tagName, //获取事件源的标签
$target = $(target), //把原生js得到的对象转化为jq对象，这样就可以用jq方法了
$pars = $target.parents(); //获取事件源得祖先元素
// 如果事件源是navBOX得A或者LI（让menuBox显示）
let flag = $pars.filter('.navBox').length>0?true:false; //TRUE包含NAV-BOX得，false则相反
if((tag==='A' || tag==='LI') && flag){
let num = $target.text().match(/\d+/);
$detailsBox.css('display','block').html(`导航${num}中对应得内容`);
return;
}
// 如果事件源是detailsBox或者是它得后代元素，不显示也不隐藏（不做处理）
if($target.hasClass('detailsBox') || $pars.filter('detailsBox').length>0){
return
}
$detailsBox.css('display','none')
})
$detailsBox.on('mouseover',function(ev){
ev.stopPropagation();
})
</script>
</body>
</html>
