My ~/.pas2js.cfg contains this line:
-Fu/home/jiutianfei/pas2js/packages/rtl
That directory looks like this:
browserconsole.pas libjquery.pas README.txt sysutils.pas
classes.pas math.pas rtlconsts.pas types.pas
contnrs.pas nodejs.pas rtti.pas typinfo.pas
dateutils.pas objpas.pas strutils.pas webgl.pas
hotreloadclient.pas pas2js_rtl.lpk system.js web.pas
js.pas pas2js_rtl.pas system.pas webrouter.pp