用Javascript做一个“获取验证码”的按钮

时间：2022-06-23 15:46:13

要求：①点击按钮后背景色会发生改变
②有倒计时（一般为30秒）

<!DOCTYPE HTML>

<html>

<head>

<meta charset="UTF-8" />

<title>pro.html</title>

<style type="text/css">

.checkCode {

    cursor: pointer;

    border: 1px solid black;

    text-align: center;

    line-height: 26px;

    width: 115px;

    height: 35px;

}

</style>

<script type="text/javascript">

    var sleep = 30, interval = null;

    window.onload = function ()

    {

        var btn = document.getElementById ('btn');

        btn.onclick = function ()

        {

            if (!interval)

            {

                this.style.backgroundColor = 'rgb(243, 182, 182)';

                this.disabled = "disabled";

                this.style.cursor = "wait";

                this.value = "重新发送 (" + sleep-- + ")";

                interval = setInterval (function ()

                {

                    if (sleep == 0)

                    {

                        if (!!interval)

                        {

                            clearInterval (interval);

                            interval = null;

                            sleep = 30;

                            btn.style.cursor = "pointer";

                            btn.removeAttribute ('disabled');

                            btn.value = "免费获取验证码";

                            btn.style.backgroundColor = '';

                        }

                        return false;

                    }

                    btn.value = "重新发送 (" + sleep-- + ")";

                }, 1000);

            }

        }

    }

</script>

</head>

<body>

    <input class="checkCode" type="button" id="btn" value="免费获取验证码" />

</body>

</html>

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