怎么实现当前时间显示并不刷新实时更新？求大神帮帮忙 _PHP

如何实现当前时间显示并不刷新实时更新？求大神帮帮忙！
如题，麻烦知道的告知下小弟，最好附上代码！谢谢！

------解决方案--------------------

HTML code


<html>
<head>
<script type="text/javascript">
function startTime()
{
var today=new Date()
var h=today.getHours()
var m=today.getMinutes()
var s=today.getSeconds()
// add a zero in front of numbers<10
m=checkTime(m)
s=checkTime(s)
document.getElementById('txt').innerHTML=h+":"+m+":"+s
t=setTimeout('startTime()',500)
}

function checkTime(i)
{
if (i<10) 
  {i="0" + i}
  return i
}
</script>
</head>

<body onload="startTime()">
<div id="txt"></div>
</body>
</html>

------解决方案--------------------

探讨

HTML code

<html>
<head>
<script type="text/javascript">
function startTime()
{
var today=new Date()
var h=today.getHours()
var m=today.getMinutes()
var s=today.getSeconds()
// add a zero in front o……