JS实现计时器，很不错的效果哦

<script language="javascript">
var se,m=0,h=0,s=0,ss=1,istrue=true;
function second(){
if((ss%100)==0){s+=1;ss=1;}
if(s>0 && (s%60)==0){m+=1;s=0;}
if(m>0 && (m%60)==0){h+=1;m=0;}
var sstext = ss < 10 ? "0"+ss : ss;
t=h+"时"+m+"分"+s+"秒"+sstext+"毫秒";
document.getElementById("showtime").innerHTML=t;
ss+=1;
}
function startclock(){if(se==null||se=='undefined'||istrue)se=setInterval("second()",1);istrue=false;}
function pauseclock(){clearInterval(se);istrue=true;}
function stopclock(){clearInterval(se);ss=1;m=h=s=0;document.getElementById("showtime").innerHTML="0时0分0秒00毫秒";istrue=true;}
</script>
<table align="center" style="margin-top:150px;">
    <tr>
        <td align="center">
            <h1 id="showtime" style="color:#ff0000;font-size:124px;">0时0分0秒00毫秒</h1><br/>
            <input style="width:100px;height:30px;font-size:20px;" name="s" align="center" type="button" value="开始计时" onclick="startclock()">
            <input style="width:100px;height:30px;font-size:20px;" name="s" align="center" type="button" value="暂停计时" onclick="pauseclock()">
            <input style="width:100px;height:30px;font-size:20px;" name="s" align="center" type="button" value="重新计时" onclick="stopclock()">
      </td>
    </tr>
</table>