发送短信倒计时

<input id="code" name="code" type="text" placeholder="验证码" maxlength="6" datatype="*" nullmsg="验证码">
<a onClick="sendMessage();" id="get_smscode"><span id="get_smscode_val">获取验证码</span></a>        



    // 发送验证码
    function sendMessage(){
        var user_telephone = $("#user_telephone").val();

        if(user_telephone == ''){
            alert("请输入手机号码");
            return false;
        }
        if(!/^1[345789]\d{9}$/.test(user_telephone)){
            alert("请输入正确的手机号码");
            return false;
        }

        var count = 60;
        var countdown;
        $.ajax({
            type:"post",
            url:"{:url('doSendMessage')}",
            data:"user_telephone="+user_telephone,//这里data传递过去的是序列化以后的字符串
            success:function(data){
                if(data.msg == '发送成功'){
                    countdown = setInterval(CountDown, 1000);
                }
            }
        });    

        // 发送短信倒计时
        function CountDown() {
          //  disabled  true可点
            $("#get_smscode").attr("disabled", true).css("background-color", "#ffffff");
            $("#get_smscode").css("color", "#cccccc");
            $("#get_smscode").css("border", "1px solid #cccccc");
            $("#get_smscode_val").html(count + "秒后获取");
            if (count == 0) {
             //  disabled  不可点
                $("#get_smscode").removeAttr("disabled").css("background-color", "#ffffff");
                $("#get_smscode").css("color", "#ee3425");
               
                $("#get_smscode_val").html("获取验证码");
                clearInterval(countdown);
            }
            count--;
        }
    }