Getting Query-String Values From Javascript

script type="text/javascript">
function GetQueryStrValFor(key)
{
var retVal="";
var query = window.location.search.substring(1);
var parms = query.split('&');
for(var i=0 to parms.length)

{ var pos = parms[i].indexOf('=');
if (pos > 0)
{
if(key==parms[i].substring(0,pos))
{
retVal= parms[i].substring(pos+1);
}
}
}
return retVal;
}

script>