{

d = new Date();

window.document.c1.f1.value =

d.getHours()+":"+d.getMinutes()+":"+d.getSeconds();

idp1=setTimeout("start();",500);

}

function stop()

{

clearTimeout(idp1);idp1=null;

}

...

<FORM NAME=c1> Текущее время:

<INPUT NAME=f1 size=8>

<INPUT TYPE=button VALUE="Start"

onClick="if(idp1==null)start();">

<INPUT TYPE=button VALUE="Stop"

onClick="if(idp1!=null)stop();">