function ChangeQueryStringValue(action,qsname,qsvalue)
{
if (action.indexOf('?') == -1 )	 //If no querystring present
return (action+"?"+qsname+"="+UrlEncode(qsvalue)); //x.asp?Name=Peter+Paul
else
{
if ( (action.indexOf("?"+qsname+"=") == -1 ) && (action.indexOf("&"+qsname+"=") == -1 ) ) //Passed querystring not already present
{
return (action+"&"+qsname+"="+UrlEncode(qsvalue)); //x.asp?Age=25&Name=Peter+Paul;
}
else //Passed Querystring already present, replace it no matter if it is ?Name= or &Name=
{
var replaceQSPrefix=(action.indexOf("?"+qsname+"=")==-1)?"&"+qsname+"=":"?"+qsname+"=";
var replaceQSSuffix=""; //This will be John in case of ?Name=John or &Name=John
startpos=action.indexOf(replaceQSPrefix);

for (a=(startpos+replaceQSPrefix.length);a<action.length;a++){
if ( action.charAt(a)=='&' ) //Next querystring beginning
break;
else
replaceQSSuffix += action.charAt(a);
	}
newaction=action.replace(replaceQSPrefix+replaceQSSuffix,replaceQSPrefix+UrlEncode(qsvalue));
return newaction;
}
}
}
function UrlEncode(text){
//text=ReplaceAll(text, "/\", "%2F");
text=ReplaceAll(text, "?", "%3F");
text=ReplaceAll(text, "=", "%3D");
text=ReplaceAll(text, "&", "%26");
text=ReplaceAll(text, " ", "+");
text=ReplaceAll(text, ",", "%2c");

return text;
}
//Replace all given string from a string
//
function ReplaceAll(varb, replaceThis, replaceBy){
newvarbarray=varb.split(replaceThis);
newvarb=newvarbarray.join(replaceBy);
return newvarb;
}