Using third-party modules (jpm)


Support for extensions using XUL/XPCOM or the Add-on SDK was removed in Firefox 57, released November 2017. As there is no supported version of Firefox enabling these technologies, this page will be removed by December 2020.

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.

Starting from Firefox 53, no new legacy add-ons will be accepted on (AMO) for desktop Firefox and Firefox for Android.

Starting from Firefox 57, only extensions developed using WebExtensions APIs will be supported on Desktop Firefox and Firefox for Android.

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 use WebExtensions APIs if they can. See the "Compatibility Milestones" document for more information.

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


The Add-on SDK includes a command-line tool that you use to initialize, run, test, and package add-ons. The current tool is called jpm, and is based on Node.js. It replaces the old cfx tool.

You can use jpm from Firefox 38 onwards.

This article describes how you can use third-party modules with jpm.

To follow this tutorial you'll need to have installed jpm and learned the basic jpm commands.

To install menuitem you'll need to have git command. If you have error related to git, check you have latest git command installed.

The Add-on SDK is extensible by design: you can use the modules that ship inside Firefox, but you can also create your own modules and make them available for anyone else to use. Before the jpm tool was available, there wasn't any package manager for these community-developed modules, so it wasn't obvious where to find community-developed modules, or how to install and update them.

With jpm, we use npm as the package manager for SDK modules that don't ship inside Firefox. Module developers can publish SDK modules to npm, and add-on developers can install them from npm and build them into their add-ons.

This article explains how to use npm-hosted third-party SDK modules with jpm. We'll use the menuitem package to add a new menu item to Firefox.


First, while in the root of your add-on, install the package that contains the modules you want to use:

npm install menuitem --save

Now you'll see a new directory in your add-on root called "node_modules" that contains a directory "menuitem". In your add-on code, you can require() modules by passing a path to the module starting from, but not including "node_modules":

var menuitems = require("menuitem");


Create a new directory called, for example, "my-menuitem", navigate to it, type "jpm init" and accept all the defaults:

mkdir my-menuitem
cd my-menuitem
jpm init

Install the menuitem package from npm:

npm install menuitem --save

This will install the package in the current directory, under a directory called "node_modules". The --save argument instructs npm to add this package to the dependencies key in the add-on's package.json file.

You'll now see a new directory in "my-menuitem" called "node_modules". It will contain a single directory "addon-pathfinder", and the modules included in this package will be somewhere in that directory:

  • my-menuitem
    • index.js
    • node_modules
      • menuitem
    • package.json
    • test

We're interested in using the "menuitem" module, which is at "addon-pathfinder/lib/ui/menuitem". Open "index.js" and replace it with this:

var menuitems = require("menuitem");

var menuitem = menuitems.Menuitem({
  id: "clickme",
  menuid: "menu_ToolsPopup",
  label: "Click Me!",
  onCommand: function() {
  insertbefore: "menu_pageInfo"

Now run the add-on:

jpm run -b nightly

You should see a new menu item in the Tools menu labeled "Click Me!". Click the button, and the message "clicked" is logged.

Note: In more recent versions of Firefox, the Menu Bar may not be visible by default. To show the Menu Bar, click on the Open Menu icon and select "Customize". Then, under Show / Hide Toolbars, enable the Menu Bar. Finally, click the green bar "Exit Customize"