console 命令行工具 X clear
console
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=, initial-scale=">
    <meta http-equiv="X-UA-Compatible" content="">
    <title></title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        .outter {
            width: 800px;
            border: 2px solid black;
            overflow: hidden;
            margin: 0 auto;
            background-color: lightyellow;
        }
        
        #left {
            width: 20%;
            height: 500px;
            float: left;
            background-color: aliceblue;
        }
        
        .right {
            width: 80%;
            height: 500px;
            float: left;
            background-color: lightyellow;
        }
        
        #bar {
            width: 30px;
            height: 50px;
            padding-left: 0px;
            background-color: grey;
        }
        
        #handle {
            width: 30px;
            height: 50px;
        }
    </style>
</head>

<body>
    <div class="outter">
        <div style="display: block;" id="left">
            <ol>
                <li>菜单1</li>
                <li>菜单2</li>
                <li>菜单3</li>
                <li>菜单4</li>
                <li>菜单5</li>
            </ol>
        </div>
        <div class="right" id="right">
            <div id="bar">
                <button id="handle" onclick="toggle('left')">隐藏</button>
            </div>
        </div>
    </div>
    <script>
        function toggle(targetid) {
            if (document.getElementById) {
                target = document.getElementById(targetid);
                if (target.style.display == "block") {
                    target.style.display = "none";
                } else {
                    target.style.display = "block";
                }
            }
        }
    </script>
</body>

</html>