<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>

</head>
<body>
    <div>
        <p id="demo">点击下方按钮显示时间</p>
        <button type="button" onclick="displayData()">北京时间</button>

    </div>
    <script>
        function displayData() {
            // 注意Date单词拼写
            document.getElementById("demo").innerHTML = Date();
        }
    </script>
</body>
</html>