30秒倒计时

 <div class="form-group">
                            <label class="col-sm-2 control-label">
                                <a href="/notice/receive/list/1">
                                    <input type="button" id="showTimes" value="已阅（30）" style="color: black" disabled/>
                                </a>

                            </label>

                        </div>
  <script>

            var ss = 30;

            //然后写一个定时器

            interval = window.setInterval(function () {
                ss--
//                document.getElementById("showTimes").innerHTML = "已阅（" + ss + "）";
                $('#showTimes').val("已阅（" + ss + "）");

                if (ss == 0) {
                    clearInterval(interval);
                    $("#showTimes").attr("disabled", false);
                    return;
                }
            }, 1000);


        </script>