You're going about it the wrong way. Native development allows you to find package names of installed apps and request they start using the Intent system with startActivity (once you verify the app exists), see here:
However that's native. You'll either need to find an existing native extension or create one yourself.
That aside facebook may supply you with the proper scheme to call to launch the app in which case it would probably prompt you to run facebook in the app or in a browser. More info on defining those schemes here with code: