mouseenter、mouseleave、mouseover和mouseout的区别

mouseenter、mouseleave、mouseover和mouseout是常用来判断鼠标移出和移入的事件句柄，虽然功能上差不多，但是细节却有不同的地方。

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>随风丶逆风</title>
    <style>
        div{
            margin: 0 auto;
        }
        .parentBox{
            height: 200px;
            width: 300px;
            background-color: #f00;
        }

        .childBox{
            height: 200px;
            width: 200px;
            background-color: #00f;
        }
    </style>
</head>
<body>
<div class="parentBox">
    <div class="childBox"></div>
</div>
</body>
<script>
    window.onload=function(){
        let parent = document.getElementsByClassName("parentBox")[0];
        parent.addEventListener("mouseenter",()=>console.log("Mouse Enter"));
        parent.addEventListener("mouseleave",()=>console.log("Mouse Leave"));
        parent.addEventListener("mouseover",()=>console.log("Mouse Over"));
        parent.addEventListener("mouseout",()=>console.log("Mouse Out"));
    }
</script>
</html>

上面是页面代码，在浏览器中打开页面，显示为下图：