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  1. Mozilla
  2. Add-ons
  3. Browser extensions
  4. JavaScript APIs
  5. i18n
  6. i18n.getSystemUILanguage()
    • Deutsch

In this article

  • Syntax
  • Browser compatibility
  1. Browser extensions
  2. Getting started
    1. What are extensions?
    2. Your first extension
    3. Your second extension
    4. Anatomy of an extension
    5. Example extensions
    6. What next?
  3. Concepts
    1. JavaScript APIs
    2. Content scripts
    3. Background scripts
    4. Match patterns
    5. Work with files
    6. Internationalization
    7. Content Security Policy
    8. Native messaging
    9. Native manifests
    10. User actions
    11. Differences between API implementations
    12. Chrome incompatibilities
  4. User interface
    1. Toolbar button
    2. Address bar button
    3. Sidebars
    4. Context menu items
    5. Options page
    6. Extension pages
    7. Notifications
    8. Address bar suggestions
    9. devtools panels
    10. Browser styles
    11. Popups
  5. How to
    1. Intercept HTTP requests
    2. Modify a web page
    3. Insert external content
    4. Share objects with page scripts
    5. Add a button to the toolbar
    6. Implement a settings page
    7. Work with the Tabs API
    8. Work with the Bookmarks API
    9. Work with the Cookies API
    10. Work with contextual identities
    11. Interact with the clipboard
    12. Extend the developer tools
    13. Build a cross-browser extension
  6. JavaScript APIs
    1. Browser support for JavaScript APIs
    2. action
    3. alarms
    4. bookmarks
    5. browserAction
    6. browserSettings
    7. browsingData
    8. captivePortal
    9. clipboard
    10. commands
    11. contentScripts
    12. contextualIdentities
    13. cookies
    14. declarativeNetRequest
    15. devtools
    16. dns
    17. dom
    18. downloads
    19. events
    20. extension
    21. extensionTypes
    22. find
    23. history
    24. i18n
      1. Methods
        1. detectLanguage()
        2. getAcceptLanguages()
        3. getMessage()
        4. getPreferredSystemLanguages()
        5. getSystemUILanguage()
        6. getUILanguage()
      2. Types
        1. LanguageCode
    25. identity
    26. idle
    27. management
    28. menus
    29. notifications
    30. omnibox
    31. pageAction
    32. permissions
    33. pkcs11
    34. privacy
    35. proxy
    36. runtime
    37. scripting
    38. search
    39. sessions
    40. sidebarAction
    41. storage
    42. tabGroups
    43. tabs
    44. theme
    45. topSites
    46. types
    47. userScripts
    48. userScripts (Legacy)
    49. webNavigation
    50. webRequest
    51. windows
  7. Manifest keys
    1. action
    2. author
    3. background
    4. browser_action
    5. browser_specific_settings
    6. chrome_settings_overrides
    7. chrome_url_overrides
    8. commands
    9. content_scripts
    10. content_security_policy
    11. declarative_net_request
    12. default_locale
    13. description
    14. developer
    15. devtools_page
    16. dictionaries
    17. externally_connectable
    18. homepage_url
    19. host_permissions
    20. icons
    21. incognito
    22. manifest_version
    23. name
    24. offline_enabled Deprecated
    25. omnibox
    26. optional_host_permissions
    27. optional_permissions
    28. options_page
    29. options_ui
    30. page_action
    31. permissions
    32. protocol_handlers
    33. short_name
    34. sidebar_action
    35. storage
    36. theme
    37. theme_experiment
    38. user_scripts
    39. version
    40. version_name
    41. web_accessible_resources
  8. Extension Workshop
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    2. Publish
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    4. Enterprise
  9. Contact us
  10. Channels
    1. Add-ons blog
    2. Add-ons forum
    3. Add-ons chat

In this article

  • Syntax
  • Browser compatibility

i18n.getSystemUILanguage()

Returns the current UI locale of the operating system. This is different from i18n.getUILanguage, which returns the UI locale of the web browser.

Syntax

js
let systemUILanguage = await browser.i18n.getSystemUILanguage()

Parameters

None.

Return value

A Promise fulfilled with a i18n.LanguageCode.

Browser compatibility

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This page was last modified on Jun 18, 2025 by MDN contributors.

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