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  6. Getting started (cfx)

Getting started (cfx)

In This Article
  1. Prerequisites
  2. Initializing an empty add-on
  3. Implementing the add-on
  4. Packaging the add-on
  5. Summary
  6. What's next?
  7. Advanced techniques
    1. Overriding the built-in modules
    2. Developing without cfx run

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.

This tutorial walks through creating a simple add-on using the cfx command-line tool.

cfx has been deprecated and you should use jpm instead. Use cfx only if you need to work with Firefox 38 or earlier. See:

  • Getting started with jpm
  • cfx to jpm

Prerequisites

To create add-ons for Firefox using the SDK, you'll first need to follow the instructions to install and activate the SDK. Once you've done that, you'll be looking at a command prompt.

Initializing an empty add-on

In the command prompt, create a new directory. The directory doesn't have to be under the SDK root: you can create it anywhere you like. Navigate to it, type cfx init, and hit enter:

mkdir my-addon
cd my-addon
cfx init

You'll see some output like this:

* lib directory created
* data directory created
* test directory created
* doc directory created
* README.md written
* package.json written
* test/test-main.js written
* lib/main.js written
* doc/main.md written
Your sample add-on is now ready for testing:
try "cfx test" and then "cfx run". Have fun!"

Implementing the add-on

Now you can write the add-on's code, which goes in the "main.js" file in your "lib" directory. This file was created for you in the previous step. Open it and add the following code:

var buttons = require('sdk/ui/button/action');
var tabs = require("sdk/tabs");
var button = buttons.ActionButton({
  id: "mozilla-link",
  label: "Visit Mozilla",
  icon: {
    "16": "./icon-16.png",
    "32": "./icon-32.png",
    "64": "./icon-64.png"
  },
  onClick: handleClick
});
function handleClick(state) {
  tabs.open("https://www.mozilla.org/");
}

Save the file.

Next, save these three icon files to the "data" directory:

icon-16.png
icon-32.png
icon-64.png

Back at the command prompt, type:

cfx run

This is the SDK command to run a new instance of Firefox with your add-on installed. When Firefox launches, in the top-right corner of the browser you'll see an icon with the Firefox logo. Click the icon, and a new tab will open with https://www.mozilla.org/ loaded into it.

That's all this add-on does. It uses two SDK modules: the action button module, which enables you to add buttons to the browser, and the tabs module, which enables you to perform basic operations with tabs. In this case, we've created a button whose icon is the Firefox icon, and added a click handler that loads the Mozilla home page in a new tab.

Try editing this file. For example, we could change the page that gets loaded:

var buttons = require('sdk/ui/button/action');
var tabs = require("sdk/tabs");
var button = buttons.ActionButton({
  id: "mozilla-link",
  label: "Visit Mozilla",
  icon: {
    "16": "./icon-16.png",
    "32": "./icon-32.png",
    "64": "./icon-64.png"
  },
  onClick: handleClick
});
function handleClick(state) {
  tabs.open("https://developer.mozilla.org/");
}

At the command prompt, execute cfx run again. This time clicking it takes you to https://developer.mozilla.org/.

Packaging the add-on

When you've finished the add-on and are ready to distribute it, you'll need to package it as an XPI file. This is the installable file format for Firefox add-ons. You can distribute XPI files yourself or publish them to https://addons.mozilla.org so other users can download and install them.

To build an XPI, just execute the command cfx xpi from the add-on's directory:

cfx xpi

You should see a message like:

Exporting extension to my-addon.xpi.

To test that this worked, try installing the XPI file in your own Firefox installation. You can do this by pressing the Ctrl+O key combination (Cmd+O on Mac) from within Firefox, or selecting the "Open" item from Firefox's "File" menu. This will bring up a file selection dialog; navigate to the "my-addon.xpi" file, open it and follow the prompts to install the add-on.

Summary

In this tutorial we've built and packaged an add-on using three commands:

  • cfx init to initialize an empty add-on template
  • cfx run to run a new instance of Firefox with the add-on installed, so we can try it out
  • cfx xpi to package the add-on into an XPI file for distribution

These are the three main commands you'll use when developing SDK add-ons. There's comprehensive reference documentation covering all the commands you can use and all the options they take.

The add-on code itself uses two SDK modules, action button and tabs. There's reference documentation for all the high-level and low-level APIs in the SDK.

What's next?

To get a feel for some of the things you can do with the SDK APIs, try working through some of the tutorials.

Advanced techniques

Overriding the built-in modules

The SDK modules you use to implement your add-on are built into Firefox. When you run or package an add-on using cfx run or cfx xpi, the add-on will use the versions of the modules in the version of Firefox that hosts it.

As an add-on developer, this is usually what you want. But if you're developing the SDK modules themselves, of course, it isn't. In this case it's assumed that you have checked out the SDK from its GitHub repo and will have run the bin/activate script from the root of your checkout.

Then when you invoke cfx run or cfx xpi, you pass the "-o" option:

cfx run -o

This instructs cfx to use the local copies of the SDK modules, not the ones in Firefox.

Developing without cfx run

Because cfx run restarts the browser each time you invoke it, it can be a little cumbersome if you are making frequent changes to an add-on. An alternative development model is to use the Extension Auto-Installer add-on: this listens for new XPI files on a specified port and installs them automatically. That way you can test new changes without needing to restart the browser:

  • make a change to your add-on
  • run cfx xpi
  • post the add-on to the port specified

You could even automate this workflow with a simple script. For example:

while true ; do cfx xpi ; wget --post-file=codesy.xpi http://localhost:8888/ ; sleep 5 ; done

Note that the logging level defined for the console is different when you use this method, compared to the logging level used when an add-on is run using cfx run. This means that if you want to see output from console.log() messages, you'll have to tweak a setting. See the documentation on logging levels for the details on this.

Another example using grunt and grunt-shell:

module.exports = function(grunt) {
  'use strict';
  require('matchdep').filterDev('grunt-!(cli)').forEach(grunt.loadNpmTasks);
  grunt.initConfig({
    shell: {
      xpi: {
        command: [
          'cd pluginpath',
          'cfx xpi',
          'wget --post-file=pluginname.xpi http://localhost:8888/ || echo>/dev/null'
        ].join('&&')
      }
    },
    watch: {
      xpi: {
        files: ['pluginpath/**'],
        tasks: ['shell:xpi']
      }
    }
  });
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-shell');
  grunt.registerTask('default', ['watch']);
};

Document Tags and Contributors

 Contributors to this page: wbamberg
 Last updated by: wbamberg, Dec 1, 2016, 10:53:00 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
    1. Add-ons blog
    2. Add-on forums
    3. Stack Overflow
    4. Development newsgroup
    5. IRC Channel