<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style>
#a{
width: 100px;
height: 100px;
background: red;
border: 1px solid;
}
#box{
width: 200px;
height: 200px;
background: blue;
border: 1px solid;
}
</style>
</head>
<body>
<div id="box">
<div id='a'></div>
</div>
</body>
</html>
<script>
document.getElementById("box").onclick=function(){
console.log("box");
}
document.getElementById("a").onclick=function(even){
even.stopPropagation (); // will even (event) as a parameter, this is the "click" event, through this even, you can get to event.target.stopPropagation () to solve the event bubbling
console.log("a"); }
</script>