DOM---鼠标事件类型（移入移出）

移入 移出mouseenter mouseleave

在父盒子上触发，在孩子盒子上不触发

移入 移出mouseover mouseout全触发

<!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>
        #box{
            width: 200px;
            height: 200px;
            background: yellow;
        }
        #child{
            width: 100px;
            height: 100px;
            background: red;
        }
    </style>
</head>
<body>
    <div id="box">鼠标移入移出
        <div id="child"></div>
    </div>
    <script>

        // 移入  移出mouseover    mouseout
        // 都触发
        box.onmouseover = function(){
            console.log("鼠标移入")
        }

        box.onmouseout = function(){
            console.log("鼠标移出")
        

        // 移入  移出mouseenter    mouseleave
        // 在父盒子上触发，在孩子盒子上不触发
        box.onmouseenter = function(){
            console.log("鼠标移入")
        }

        box.onmouseleave = function(){
            console.log("鼠标移出")
        }
    </script>
</body>
</html>