Enable Error Console with -jsconsole to debug your app inside the WebApp runtime.
To debug problems when your app is running inside the WebApp runtime, enable the Error Console and run the app from the command line:
$ ~/.http\;alcacoop.github.com/webapprt-srt -jsconsole
See also
- Hacking Firefox OS for more information on debugging
- bug 829573: When using the Web runtime, console methods should output to stdout