This is a command line tool to help build, run, and test WebExtensions.
Ultimately, it aims to support browser extensions in a standard, portable, cross-platform way. Initially, it will provide a streamlined experience for developing Firefox Extensions.
Here are the commands you can run. Click on each one for detailed documentation or use
--help on the command line, such as
web-ext build --help.
- Run the extension
- Validate the extension source
- Sign the extension so it can be installed in Firefox
- Create an extension package from source
- Open the
web-extdocumentation in a browser
- Open the
Installation from npm
You can install this command onto your machine globally with:
npm install --global web-ext
For your project
Alternatively, you can install this command as one of the
of your project. This method can help you control the version of
as used by your team.
npm install --save-dev web-ext
Next you can use the
web-ext command in your project as an
Here is an example where the
--source-dir argument specifies where to find
the source code for your extension.
You can always pass in additional commands to your npm scripts using
-- suffix. For example, the previous script could specify the Firefox
version on the command line with this:
npm run start:firefox -- --firefox=nightly
Installation from source
Optionally, you may like:
- nvm, which helps manage node versions
If you had already installed
web-ext from npm,
you may need to uninstall it first:
npm uninstall --global web-ext
Change into the source and install all dependencies:
git clone https://github.com/mozilla/web-ext.git cd web-ext npm install
Build the command:
npm run build
Link it to your node installation:
You can now run it from any directory:
To get updates, just pull changes and rebuild the executable. You don't need to relink it.
cd /path/to/web-ext git pull npm run build
Using web-ext in NodeJS code
Aside from using web-ext on the command line, you may wish to execute
web-ext in NodeJS code. There is limited support for this. Here are some examples.
You are able to execute command functions without any argument validation. If you want to execute
web-ext run you would do so like this:
// const webExt = require('web-ext').default;// or...;webExtcmd;
If you would like to control logging, you can access the logger object. Here is an example of turning on verbose logging:
You can also disable the use of standard input:
web-ext is designed for WebExtensions but you can try disabling manifest validation to work with legacy extensions. This is not officially supported.
Should I Use It?
Yes! The web-ext tool enables you to build and ship extensions for Firefox. This platform stabilized in Firefox 48 which was released in April of 2016.
Hi! This tool is under active development. To get involved you can watch the repo, file issues, create pull requests, or ask a question on dev-addons. Read the contributing section for how to develop new features.
Some Questions and Answers
Why do we need a command line tool?
This is a great question and one that we will ask ourselves for each new web-ext feature. Most WebExtension functionality is baked into the browsers themselves but a complimentary command line tool will still be helpful. Here is a partial list of examples:
- File watching.
- When you edit a file, you may need to trigger certain commands (tests, installation, etc).
- Integrating with services.
Why not patch jpm for WebExtensions support?
Mozilla built cfx then deprecated it for jpm and now we're proposing a new tool. I know this is frustrating for developers, but WebExtensions mark a major turning point. It would be an arduous task to wedge its feature set and simplified development process into jpm.
Pros of creating a new tool:
- By creating a new tool that focuses on the [emerging] WebExtensions standard, we have a better chance of interoperating with other platforms, such as Google Chrome or Opera. It would be hard to do that while preserving compatibility in jpm.
- Creating SDK-based add-ons was overly complicated. With WebExtensions you no longer need to convert your source into legacy artifacts and you won't need boostrapping scripts.
- There are superior features in Firefox now for developing extensions such as loading from source code instead of a packaged XPI. It will be easier to reimagine a new tool around these work flows rather than adjust jpm's existing work flows.
- jpm's functional tests are slow, brittle and hard to run. There are flaky time-outs and we've run out of low hanging fruit fixes at this point.
- Most of jpm's code was not designed to be unit testable which makes it hard to maintain and refactor.
- jpm's code was written in ES5 which is cumbersome after coming from the ES6 Firefox code base or from most other languages with modern conveniences (Python, Ruby, etc).
- Some core functionality of jpm can be extracted and re-used in the new tool.
Cons of creating a new tool:
- Firefox extension developers will have to interrupt and re-arrange their work flows.
- Developers of existing add-ons will need to port to WebExtensions sooner rather than later.
- The web-ext tool will require some ramp-up time for scaffolding.
- The community of jpm contributors will need to shift focus to web-ext.