2022-12-12T15:12:31.png

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>第一个JS</title>
    <style>
        #div1 {
            width: 100px;
            height: 100px;
            background-color: red;
            border: 1px solid gold;
            display: none;
        }
    </style>
    <script>
        function f() {
            document.getElementById('div1').style.display = 'block'
        }
 
        function f1() {
            document.getElementById('div1').style.display = 'none'
        }
    </script>
</head>
<body>
<input type="checkbox" id="in1" onmouseover=f() onmouseout=f1() />
<div id="div1">
    这是一个JS代码
</div>
</body>
</html>