js实现简单的获取验证码按钮效果

.checkCode {

  cursor: pointer;

  border: 1px solid black;

  text-align: center;

  line-height: 26px;

  width: 115px;

  height: 35px;

}

  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);

      }

    }

  }