Javascript to refresh page

use following script

<script type="text/javascript">
<!--

/*
Auto Refresh Page with Time script
opensourzesupport
*/

//enter refresh time in "minutes:seconds" Minutes should range from 0 to inifinity. Seconds should range from 0 to 59
var limit="0:30"

if (document.images){
var parselimit=limit.split(":")
parselimit=parselimit[0]*60+parselimit[1]*1
}
function beginrefresh(){
if (!document.images)
return
if (parselimit==1)
window.location.reload()
else{
parselimit-=1
curmin=Math.floor(parselimit/60)
cursec=parselimit%60
if (curmin!=0)
curtime=curmin+" minutes and "+cursec+" seconds left until page refresh!"
else
curtime=cursec+" seconds left until page refresh!"
window.status=curtime
setTimeout("beginrefresh()",1000)
}
}

window.onload=beginrefresh
//-->
</script>