js实现发送验证码倒计时效果

<!doctype html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Document</title>

    <style>

        #btnyzm {

    background: #31BCFF;

    color: #fff;

    font-size: 14px;

    padding: 0;

    line-height: 43px;

    border-radius: 0;

    border: 0;

    width: 50%;

}

.btn_com:disabled {

    background-color: #999999 !important;

}

    </style>

</head>

<body>

    <input type="button" class="btn_com" id="btnyzm" value="发送验证码">

<script type="text/javascript">

        var wait=60;

        function time(o) {

            if (wait == 0) {

                o.removeAttribute("disabled");

                o.value="发送验证码";

                wait = 60;

            } else {

                o.setAttribute("disabled", true);

                o.value="(" + wait + ")后可重新发送";

                wait--;

                setTimeout(function() {

                    time(o)

                }, 1000)

            }

        }

        document.getElementById("btnyzm").onclick=function(){time(this);}

    </script>

</body>

</html>