webextensions-examples

https://github.com/mdn/webextensions-examples

Maintained by Mozilla’s Add-ons team.

WebExtensions are a way to write browser extensions: that is, programs
installed inside a web browser that modify the behavior of the browser or
web pages loaded by the browser. WebExtensions are built on a set of
cross-browser APIs, so WebExtensions written for Google Chrome, Opera, or
Edge will, in most cases, run in Firefox too.

The “webextensions-examples” repository is a collection of simple,
complete, and installable WebExtensions. The examples show how to use the
WebExtensions APIs, and you can use them as a starting point for your
WebExtensions.

For an index of all the examples, see the “Example extensions” page on MDN.

The examples are made available under the
Mozilla Public License 2.0.

How to use “webextensions-examples”

To use the repository, first clone it.

Each example is in a top-level folder and includes a short README explaining
what it does. To see how an example works, install it in Firefox by following
the installation instructions.

To find your way around a WebExtension’s internal structure, have a look at the
Anatomy of a WebExtension
page on MDN.

To use these examples in Firefox, use the most recent release of Firefox.
However, most examples work with earlier releases.

A few examples rely on APIs that are only available in pre-release versions
of Firefox. Where this is the case, the example declares the minimum version
that it needs in the strict_min_version attribute of the
browser_specific_settings key
in the extension’s manifest.json file.

Installing an example

Some examples work only on specific domains or pages. Details of any
restrictions are provided in each example’s README file. None of the
examples work in private browsing windows by default, see
Extensions in Private Browsing
for details.

To run an example extension:

1. Open Firefox and load the about:debugging page. Click
   Load Temporary Add-on
   and select the manifest.json file within the folder of an example extension.
   Here is a video
   that demonstrates how to do this.
2. Install the
   web-ext
   tool. At the command line, open the example extension’s folder and type
   web-ext run. This launches Firefox and installs the extension automatically.
   This tool provides some additional development features, such as
   automatic reloading.

Support for other browsers

These examples are tested in Firefox. They may work in other browsers, if the
browser supports the APIs used.
Note that these examples all use the browser namespace and promises to
work with asynchronous functions. This means the examples won’t work in
Chrome unless you use the
polyfill provided by Mozilla.
See the overview of WebExtension APIs
for more information.

Learn more

To learn more about developing WebExtensions, see the
WebExtensions documentation on MDN
for getting started guides, tutorials, and full API reference docs.

Problems?

If you encounter an issue:

• post a query on the add-ons discourse forum
• email the dev-addons mailing list
• contact the add-ons team in the Add-ons room on Matrix

If you cannot resolve the issue, file a bug.

Contributing

We welcome contributions, whether they are new examples, new features, bug
fixes, or translations of localizable strings. Please see the
CONTRIBUTING.md
file for more details.