Browser Add-ons, Google Chrome, Mozilla, Mozilla Firefox, Programming

Using Google Chrome locale files in Firefox extensions, updated

After I posted my latest revision to some code for using Google Chrome locale files in Firefox extensions, Wladimir Palant pointed out some shortcomings with the code; I’ve made some changes to address these issues, and the new code is shown below.

View the code at GitHub.


The new usage rules are as follows:

  • Replace MY_EXTENSION_NAMESPACE with the namespace of your extension’s files. e.g., if your files are at chrome://abcdefg/content/, then replace MY_EXTENSION_NAMESPACE with abcdefg.
  • Rename MY_EXTENSION_STRINGS to something that won’t interfere with another extension.
  • The _locales directory from your Chrome extension should be in the chrome/content/ directory of your Firefox extension (or update my code to point to wherever you put it).


This code has four advantages over the previous versions:

  1. It’s a single code block that works with all recent versions of Firefox.
  2. You don’t need to include an additional library for file I/O.
  3. It fixes a bug in retrieving the proper locale code in Firefox on Linux.
  4. You don’t have to specify <em:unpack>true</em:unpack> in your install.rdf in Firefox 4.

Thanks Wladimir for your input; this version is undoubtedly better than both previous versions. I can’t ensure that it’s the best possible solution, but it’s the best one that I’ve found so far.


6 comments on “Using Google Chrome locale files in Firefox extensions, updated

  1. Thank you, that’s better (though personally I prefer using “native” string formats both in Chrome and Firefox and converting between the two when packaging). A minor issue: I think that you either need to pass in MY_EXTENSION_STRINGS.strings in the last line or change the assignment into |string_object.strings[i] = messages[i]|.

  2. You are correct about the MY_EXTENSION_STRINGS.strings issue; I’ve fixed it in the code sample.

    This method definitely won’t be for everyone, but for ScribeFire, where 99% of the functionality is inside a single HTML webpage that is run in Firefox, Chrome, Safari, and Opera, choosing a single locale format and method for loading strings cuts way down on the complexity of localizing in each browser.

  3. IT Rush: What specifically do you need help with? To use the code above, include it in your extension, and then call MY_EXTENSION_STRINGS.get(“string_key_foo”) to get the localized version of string_key_foo.

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