JS实现动态显示当前时间

效果图：

代码实现：

  <script language="JavaScript">
                     var timerID = null;
                     var timerRunning = false;
                     function stopclock() {
                         if (timerRunning)
                             clearTimeout(timerID);
                         timerRunning = false;
                     }
                     function startclock() {
                         stopclock();
                         showtime();
                     }
                     function showtime() {
                         var now = new Date();
                         var year = now.getFullYear();
                         var month = now.getMonth() + 1;
                         var day = now.getDate();
                         var hours = now.getHours();
                         var minutes = now.getMinutes();
                         var seconds = now.getSeconds()
                         var timeValue = "系统时间: " + year + "-" + ((month >= 10) ? month : "0" + month) + "-" + ((day >= 10) ? day : "0" + day) + "  ";

                         timeValue += ((hours < 10) ? "0":"")+hours
                         timeValue += ((minutes < 10) ? ":0" : ":") + minutes
                         timeValue += ((seconds < 10) ? ":0" : ":") + seconds
                         document.clock.thetime.value = timeValue;
                         timerID = setTimeout("showtime()", 1000);
                         timerRunning = true;
                     }

                 </script>

 <form name="clock" style="float:right;width:360px;padding-top:5px;">
     <span style="vertical-align: central;">
        <input name="thetime" size="30" style="font-size: 14px; background-color: transparent; border: 0; color: #49d1fe ; font-weight: 600; ">
     </span>
  </form>