[Commons-l] Javascript I18n

[Dschwen]

In its current state of i18n in our javascript is broken at best.

The i18n stuff will not work in Monobook.js as it is. Loading a 
subpage 'monobook.js/'+wgUserLanguage is a nice idea, but such script 
includes are only queued by the includePage()! The scripts are '''not''' 
loaded immediately, and thus the translation strings are not available to the 
scripts on the page.

It won't help to move the i18n stuff to Common.js, as Common.js and 
Monobook.js are delivered to the client as one chunk.

We need another layer of includes in our script system to get the execution 
order right, and I propose the following:

1. in MediaWiki:Common.js only skin-non-specific helperfunctions which require 
no string translations should be permitted

2. No user extension function should be included directly from Common.js or be 
put into Common.js (see 1.)

3. To the bottom of the Common.js add two includePage calls:
   includePage( 'MediaWiki:Common.js/' + wgUserLanguage );
   includePage( 'MediaWiki:Common.js/' + skin + '/' + wgUserLanguage );
  for global and skinspecific i18n strings.

4. For practical purposes '''always''' include the english translation, which 
should serve as the base translation. Only execute the other two includes if 
wgUserLanguage != 'en'.
This will permit incomplete or missing translations, enabling english as a 
fallback.

5. To the bottom of the Common.js add one more includePage call:
   includePage( 'MediaWiki:Common.js/Extensions' );
  for extensions that should be included in every skin

6. In MediaWiki:Common.js/Extensions add small scripts and includePage calls 
for larger scripts. The MediaWiki:Common.js/Extensions page will be executed 
_after_ the whole i18n system and thus the i18n strings will be available to 
the extensions, allowing for a unified JS-i18n system

6. in MediaWiki:Monobook.js only skin-specific helperfunctions should be 
included which require no string translations.

5. To the bottom of the Monobook.js add one more includePage call:
   includePage( 'MediaWiki:Monobook.js/Extensions' );
  for monobook specific extensions

Note that Common.js and Monobook.js are delivered en-block as the first 
scripts which we (the non-developer admins) can influence. 

P.S.: replace Monobook.js with your favourite skin, I just used it as an 
example.
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