Fiddler Change parameter post request and postdata OnBeforeRequest -

i want change name of parameter before request here special function nothing works

static function replacequeryparameter(sname: string, svalue: string) {     var re:regexp;     if (svalue == null) {         re = new regexp( "(" + sname + "=)(([^&]*)|$)");      var   ret = gs_querystring.replace(re, '');         gs_querystring = ret;     }     else {         re = new regexp( "(" + sname + "=)(([^&]*)|$)");        var ret = gs_querystring.replace(re, "$1" + svalue);         gs_querystring = ret;     } }     static function onbeforerequest(osession: session) {       gs_querystring = system.text.encoding.utf8.getstring(osession.requestbodybytes);     replacequeryparameter('username','username1');           setbodyfromquerystring(osession);  } 

any help?

there multiple problems code. 1 thing, looks you're trying share single variable ("gs_querystring") across multiple requests. going result in race conditions , corruptions multiple sessions execute in parallel.

you're getting confused data in request.

the requestbodybytes byte[] contains bytes in body of post or put. doesn't have body bytes.

the url string contains url including querystring parameters. requests have url.

if you're trying change querystring, part of url, use:

var gs_querystring = osession.url; osession.url = replacequeryparameter('username','username1'); 

...and update replacequeryparameter function return value instead of trying update unprotected shared variable.