mousemove触发时会发生冒泡，子元素也会触发事件
mouseenter不出触发事件冒泡，对应mouseleave
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.father {
width: 200px;
height: 200px;
background-color: pink;
}
.son {
width: 100px;
height: 100px;
background-color: yellow;
}
</style>
</head>
<body>
<div class="father">
<div class="son"></div>
</div>
<script>
var father = document.querySelector('.father');
//mouseover会发生冒泡，移动到子元素的时候也会触发事件
//mouseenter 不会发生冒泡
father.addEventListener('mouseenter',function(){
console.log('11');
})
</script>
</body>
</html>