<script type="text/javascript">

var iText=document.getElementById("clock");

var c=setInterval(begin,100);

function begin(){

var time=new Date();

var s=time.getSeconds();

//三目运算:

var h=time.getHours();h=(h<10)?"0"+h:h;

var m=time.getMinutes();m=(m<10)?"0"+m:m;

var s=time.getSeconds();s=(s<10)?"0"+s:s;

document.getElementById("clock").value = h+":"+m+":"+s;}

</script>