老师帮看下第三个为什么会掉下来

来源：3-13 编程练习

weixin_慕尼黑0465866

2023-02-27 11:16:38

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>Document</title>
    <style>
        div {
            width: 300px;
            margin: 20px 0;
            line-height: 30px;
            background: yellowgreen;
        }
    </style>
</head>

<body>
    <button id="start">开始</button>
    <button id="stop">停止</button>
    <div id="box"></div>
    <script>
        const startBtn = document.getElementById('start')
        const stopBtn = document.getElementById('stop')
        const box = document.getElementById('box')
        var show = {
            content: "Hello World",
            timer: null,
            start: function () {
                // 在此补充代码
                startBtn.onclick = () => {
                    clearInterval(this.timer)
                    this.timer = setInterval(() => {
                        box.innerHTML += this.content+"&nbsp;";
                    }, 1000)
                }
            },
            stop: function () {
                // 在此补充代码
                stopBtn.onclick = () => {
                    clearInterval(this.timer)
                }
            },
        }
        // 在此补充代码
        show.start();
        show.stop();
    </script>
</body>

</html>

写回答

1回答