Digital Clock Program in Java Script

Current Time: <span id="txt"></span>
<script>

window.onload=function(){getTime();}

function getTime()
{
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;

setInterval("getTime()",1000);//another way

}

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