jq获取短信验证码点击倒计时效果

前端 html：

<div class="row cl">
            <label class="form-label col-xs-3 col-sm-2 col-md-2"><span class="c-red">*</span>短信验证码：</label>
            <div class="formControls col-xs-2 col-sm-2">
                <input type="text" class="input-text" value="" name="smsyzm" id="smsyzm" required="required">
            </div>
            <div class="formControls col-xs-2 col-sm-2">
                <input id="smsyzm0" class="btn btn-warning  size-M radius" type="button" value="免费获取验证码" onclick="sendsms(this)" >
            </div>
        </div>

<label class="form-label col-xs-3 col-sm-2 col-md-2"><span class="c-red">*</span>短信验证码：</label>

</div>

</div>

前端js代码：

var countdown=parseInt(60);
var sending = false;
$(function () {
    //countdown = $.cookie('validateCodeCountdown');
    countdown=60;
    if (countdown>0) {
        sending = true;
        var obj = $("#btn");
        obj.attr("disabled", true);
        obj.val("重新发送(" + countdown + ")");
    }
});

function sendsms() {
    var getmobile = $("#mobile").val();
    if(getmobile==''){
        layer.alert("手机号码不能为空",{icon:2});
    }else{
        sendnumber(getmobile);
        sending = true;
        var obj = $("#smsyzm0");
        settime(obj);
    }
}
function settime(obj) { //发送验证码倒计时
    if (countdown == 0) {
        $("#smsyzm0").removeClass("disabled").addClass("btn-warnin");
        obj.attr('disabled', false);
        obj.val("发送验证码");
        countdown = 60;
        sending = false;
        return;
    } else {
        $("#smsyzm0").removeClass("btn-warnin").addClass("disabled");
        obj.attr('disabled', true);
        obj.val("重新发送(" + countdown + ")");
        countdown--;
    }
    setTimeout(function () {
        settime(obj);
    }, 1000)
}

function sendnumber(phone) {
    $.post('/admin/sms', {phone:phone},
        function(data){
            //console.log(data);
        })
}