While the XPages Extension Library contains a control to use the firebug lite control, you might want to use it to debug a production app and or an Angular application which is not residing within XPages. You can do this on Firefox by installing the plugin, but it gets harder when you are testing cross multiple browsers and especially on an iPad where the development tools are limited.

You can install firebug lite as a bookmarklet within your iPad bookmarks by following the instructions on this site:

http://iosbookmarklets.com/tutorials/firebug-lite-bookmarklet-ipad/

Using the link you can then debug (with some difficulty but way better than nothing) your applications by looking at the in and out-going traffic from the page.