()这里用的是input做的点击发送验证码
<input type="number" class="input" name="mobile" placeholder="手机号" style="border: none"

<input class="hui_kuang"style="width: 30%;text-align: center;height: 42px"onclick="setTime(this)" value='获取验证码'>
<script>
　　
//页面初始化获取倒计时数字（避免在倒计时时用户刷新浏览器导致倒计时归零）
 var $getCodeInput = $(".hui_kuang");
 var sessionCountdown = sessionStorage.getItem("countdown");
 if (!sessionCountdown) {
  $(".hui_kuang").val("获取验证码")
 } else {
  $(".hui_kuang").val("重新发送(" + sessionCountdown + ")");
  setCode($getCodeInput, sessionCountdown);
 }
 //获取验证码
 function setTime() {
  var remobile = $("#registForm input[name='mobile']").val();
  if (!remobile) {
   alert("请输入手机号码")
   return;

  }
  if (!(/^1[3|4|5|8][0-9]\d{4,8}$/.test(remobile))) {
   alert("请输入有效的手机号码")
   return;
  } else {
   setCode($getCodeInput, 60);
  }

 }
 //发送验证码倒计时
 function setCode($getCodeInput, countdown) {
  if (countdown == 0) {
   $getCodeInput.attr('disabled', false);
//   $getCodeInput.removeAttribute("disabled");
   $getCodeInput.val("获取验证码");
   sessionStorage.removeItem("countdown");
   return;
  } else {
   $getCodeInput.attr('disabled', true);
   $getCodeInput.val("重新发送(" + countdown + ")");
   countdown--;
  }
  sessionStorage.setItem("countdown", countdown);
  window.setTimeout(function () {
   setCode($getCodeInput, countdown);
  }, 1000);
 }
</script>