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  6. l10n

l10n

In This Article
  1. Usage
  2. Globals
    1. Functions
      1. get(identifier, count, placeholder1...n)

Add-ons using the techniques described in this document are considered a legacy technology in Firefox. Don't use these techniques to develop new add-ons. Use WebExtensions instead. If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions.

From Firefox 53 onwards, no new legacy add-ons will be accepted on addons.mozilla.org (AMO).

From Firefox 57 onwards, WebExtensions will be the only supported extension type, and Firefox will not load other types.

Even before Firefox 57, changes coming up in the Firefox platform will break many legacy extensions. These changes include multiprocess Firefox (e10s), sandboxing, and multiple content processes. Legacy extensions that are affected by these changes should migrate to WebExtensions if they can. See the "Compatibility Milestones" document for more.

A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.

Stable

Localize strings appearing in the add-on's JavaScript code.

Usage

To learn how to use this module to write localizable code, read the Localization tutorial.

Note that you can't currently use localize strings appearing in content scripts or HTML files, but you can share the localized strings you want by assigning it's values to a JSON serializable object.

Globals

Functions

get(identifier, count, placeholder1...n)

This function takes a string parameter which it uses as an identifier to look up and return a localized string in the locale currently set for Firefox. Localized strings are supplied by the add-on developer in .properties files stored in the add-ons "locale" directory.

The gettext tools uses "_" for the name of the function that retrieves localized strings. For compatibility with tools that expect this syntax, you can assign this function to "_":

var _ = require("sdk/l10n").get;

Given a .properties file for the current locale containing an entry like:

hello_string= Hello!

and the following code:

var _ = require("sdk/l10n").get;
console.log(_("hello_string"));

the following output will be logged:

info: Hello!

If this function can't find the string referenced by the identifier parameter, it returns the identifier itself. This enables you to write functional, localizable code without localizing any strings - just make the identifiers the default language:

var _ = require("sdk/l10n").get;
console.log(_("Hello!"));

However, this will make it more difficult to maintain your code if you have many localizations, because any changes to the identifier values break all your .properties files.

If you're supplying different localizations for a string depending on the number of items (that is, whether to use a singular or plural form) then get() takes a second integer parameter which indicates the number of items there are.

You can supply one or more placeholders to get(), which are strings, such as proper names, that should not be translated themselves but instead should be inserted into the translated string.

You can't use plurals and placeholders in the same expression: if you do, the placeholders will be ignored.

Parameters

identifier : string
A identifier for the localization of a particular string in the current locale.

count : integer
Optional parameter. If you're supplying different localizations for a string for singular or plural forms, this parameter is the number of items there are in this case.

var _ = require("sdk/l10n").get;
console.log(_("child_id", 1));
console.log(_("child_id", 2));

See the tutorial on plural support for more information.

Note that if you use this parameter, you can't supply any placeholders.

placeholder1...n : string
Optional parameters. If you do not include the count parameter, you can supply one or more placeholder strings that are to be inserted into the translated string at locations defined by the translator.

If you supply multiple placeholders, each one is a separate string parameter.

var _ = require("sdk/l10n").get;
console.log(_("home_town", "Alan", "Norwich"));

See the tutorial on placeholder support for more information.

Returns

string : The localized string referenced by the identifier parameter passed in, or the identifier itself if no referent for the identifier can be found.

Document Tags and Contributors

Tags: 
  • Add-on SDK
 Contributors to this page: wbamberg, gal007, olsh
 Last updated by: wbamberg, Dec 1, 2016, 10:21:36 AM
See also
  1. WebExtensions
  2. Getting started
    1. What are WebExtensions?
    2. Your first WebExtension
    3. Your second WebExtension
    4. Anatomy of a WebExtension
    5. Example WebExtensions
  3. How to
    1. Intercept HTTP requests
    2. Modify a web page
    3. Add a button to the toolbar
    4. Implement a settings page
  4. Concepts
    1. Using the JavaScript APIs
    2. User interface components
    3. Content scripts
    4. Match patterns
    5. Internationalization
    6. Content Security Policy
    7. Native messaging
  5. Porting
    1. Porting a Google Chrome extension
    2. Porting a legacy Firefox add-on
    3. Embedded WebExtensions
    4. Comparison with the Add-on SDK
    5. Comparison with XUL/XPCOM extensions
    6. Chrome incompatibilities
  6. Firefox workflow
    1. Temporary Installation in Firefox
    2. Debugging
    3. Getting started with web-ext
    4. web-ext command reference
    5. WebExtensions and the Add-on ID
    6. Publishing your WebExtension
  7. JavaScript APIs
    1. Browser support for JavaScript APIs
    2. alarms
    3. bookmarks
    4. browserAction
    5. browsingData
    6. commands
    7. contextMenus
    8. contextualIdentities
    9. cookies
    10. downloads
    11. events
    12. extension
    13. extensionTypes
    14. history
    15. i18n
    16. identity
    17. idle
    18. management
    19. notifications
    20. omnibox
    21. pageAction
    22. runtime
    23. sessions
    24. sidebarAction
    25. storage
    26. tabs
    27. topSites
    28. webNavigation
    29. webRequest
    30. windows
  8. Manifest keys
    1. applications
    2. author
    3. background
    4. browser_action
    5. chrome_url_overrides
    6. commands
    7. content_scripts
    8. content_security_policy
    9. default_locale
    10. description
    11. developer
    12. homepage_url
    13. icons
    14. manifest_version
    15. name
    16. omnibox
    17. options_ui
    18. page_action
    19. permissions
    20. short_name
    21. sidebar_action
    22. version
    23. web_accessible_resources
  9. Add-on SDK
  10. Getting started
    1. Installation
    2. Getting started
    3. Troubleshooting
  11. High-Level APIs
    1. addon-page
    2. base64
    3. clipboard
    4. context-menu
    5. hotkeys
    6. indexed-db
    7. l10n
    8. notifications
    9. page-mod
    10. page-worker
    11. panel
    12. passwords
    13. private-browsing
    14. querystring
    15. request
    16. selection
    17. self
    18. simple-prefs
    19. simple-storage
    20. system
    21. tabs
    22. timers
    23. ui
    24. url
    25. webextension
    26. widget
    27. windows
  12. Low-Level APIs
    1. /loader
    2. chrome
    3. console/plain-text
    4. console/traceback
    5. content/content
    6. content/loader
    7. content/mod
    8. content/symbiont
    9. content/worker
    10. core/heritage
    11. core/namespace
    12. core/promise
    13. dev/panel
    14. event/core
    15. event/target
    16. frame/hidden-frame
    17. frame/utils
    18. fs/path
    19. io/byte-streams
    20. io/file
    21. io/text-streams
    22. lang/functional
    23. lang/type
    24. loader/cuddlefish
    25. loader/sandbox
    26. net/url
    27. net/xhr
    28. places/bookmarks
    29. places/favicon
    30. places/history
    31. platform/xpcom
    32. preferences/event-target
    33. preferences/service
    34. remote/child
    35. remote/parent
    36. stylesheet/style
    37. stylesheet/utils
    38. system/child_process
    39. system/environment
    40. system/events
    41. system/runtime
    42. system/unload
    43. system/xul-app
    44. tabs/utils
    45. test/assert
    46. test/harness
    47. test/httpd
    48. test/runner
    49. test/utils
    50. ui/button/action
    51. ui/button/toggle
    52. ui/frame
    53. ui/id
    54. ui/sidebar
    55. ui/toolbar
    56. util/array
    57. util/collection
    58. util/deprecate
    59. util/list
    60. util/match-pattern
    61. util/object
    62. util/uuid
    63. window/utils
  13. Firefox for Android
  14. Getting started
    1. Walkthrough
    2. Debugging
    3. Code snippets
  15. APIs
    1. Accounts.jsm
    2. BrowserApp
    3. HelperApps.jsm
    4. Home.jsm
    5. HomeProvider.jsm
    6. JavaAddonManager.jsm
    7. NativeWindow
    8. Notifications.jsm
    9. PageActions.jsm
    10. Prompt.jsm
    11. RuntimePermissions.jsm
    12. Snackbars.jsm
    13. Sound.jsm
    14. Tab
  16. Legacy
  17. Restartless extensions
    1. Overview
  18. Overlay extensions
    1. Overview
  19. Themes
  20. Lightweight themes
    1. Overview
  21. Complete themes
    1. Overview
  22. Publishing add-ons
  23. Guides
    1. Signing and distribution overview
    2. Submit an add-on
    3. Review policies
    4. Developer agreement
    5. Featured add-ons
    6. Contact addons.mozilla.org
  24. Community and support
  25. Channels
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    2. Add-on forums
    3. Stack Overflow
    4. Development newsgroup
    5. IRC Channel