一个事件冒泡的例子：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript" src="jquery-1.12.4.min.js"></script>
<script type="text/javascript">
$(function () {
$('body').click(function () {
alert(4);
});
$('.grandfather').click(function () {
alert(3);
});
$('.father').click(function () {
alert(2);
});
$('.son').click(function () {
alert(1);
});
})
</script>
<style type="text/css">
.grandfather{
width:300px;
height:300px;
background-color: gold;
position: relative;
}
.father{
width:200px;
height:200px;
background-color: hotpink;
}
.son{
width:100px;
height:100px;
background-color: chartreuse;
position: absolute;
left:0;
top:400px;
}
</style>
</head>
<body>
<div class="grandfather">
<div class="father">
<div class="son"></div>
</div>
</div>
</body>
</html>
事件冒泡有时候是不需要的，需要阻止掉，通过event.stopPropagation()来阻止