JavaScript 实现支付页面 10 秒倒计时跳转功能

<!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>
        #btn{
            display: block;
            margin:130px auto;
            width: 300px;
            height: 100px;
            font-size:30px;
        }
    </style>
</head>
<body>
    <button id="btn">支付</button>
    <script>
        let btn=document.getElementById("btn");
        
        btn.onclick=function(){
            let con=window.confirm("您确定吗？");
            if(con){
                location.href='./支付.html';
            }
        }
    </script>
</body>
</html>

<!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>
        #spa {
            font-size: 20px;
            color: red;
        }

        #total {
            width: 200px;
            height: 200px;
            background-color: rgba(169, 169, 169, 0.315);
            margin: 40px auto;
            border-radius: 20px;
            padding: 20px;
            position: flex;
            flex-direction: column;
            text-align: center;
        }

        #total h3 {
            padding-top: 20px;
        }

        #total button {
            margin-top: 30px
        }
    </style>
</head>

<body>
    <div id="total">
        <h3>恭喜您，支付成功！</h3>
        <div>
            <span id="spa">10</span>
            <span>秒后自动返回首页</span>
        </div>
        <button id="btn">立即返回</button>
    </div>
    <script>
        var spa = document.getElementById("spa");
        let t = 10;
        setInterval(() => {
            t--;
            spa.innerText = t;
            if (t == 0) {
                location.href = "./支付10秒钟.html";
            }
        }, 400);
        
        var btn=document.getElementById("btn");
        btn.onclick=function(){
            location.href="./支付10秒钟.html" rel="external nofollow" 
        }
    </script>
</body>

</html>