Example extensions

To help illustrate how to develop extensions, we maintain a repository of simple example extensions at https://github.com/mdn/webextensions-examples. This article describes the WebExtension APIs used in that repository.

These examples work in Firefox Nightly: most work in earlier versions of Firefox, but check the strict_min_version key in the extension's manifest.json to make sure.

If you want to try out these examples, you have three main choices:

Clone the repository, then load the extension straight from its source directory, using the "Load Temporary Add-on" feature. The extension will stay loaded until you restart Firefox.
Clone the repository, then use the web-ext command line tool to run Firefox with the extension installed.
Clone the repository, then go to the build directory. This contains built and signed versions of all the examples, so you can just open them in Firefox (using File/Open File) and install them permanently, just like an extension you would install from addons.mozilla.org.

If you want to contribute to the repository, send us a pull request!

Name	Description	JavaScript APIs
annotate-page	Displays a sidebar that lets you take notes on web pages.	`storage.local` `tabs.onActivated` `tabs.onUpdated` `tabs.query` `windows.getCurrent`
apply-css	Adds a page action to the toolbar. Click the button to apply a red border using injected CSS. Click the button again to remove the CSS.	`pageAction.getTitle` `pageAction.onClicked` `pageAction.setIcon` `pageAction.setTitle` `pageAction.show` `tabs.insertCSS` `tabs.onUpdated` `tabs.query` `tabs.removeCSS`
beastify	Adds a browser action icon to the toolbar. Click the button to choose a beast. The active tab's body content is then replaced with a picture of the chosen beast.	`extension.getURL` `runtime.onMessage` `tabs.executeScript` `tabs.query` `tabs.reload` `tabs.sendMessage`
bookmark-it	Adds a bookmark button to the toolbar. Click the button to toggle a bookmark for the current page.	`bookmarks.create` `bookmarks.onCreated` `bookmarks.onRemoved` `bookmarks.remove` `bookmarks.search` `browserAction.onClicked` `browserAction.setIcon` `tabs.onActivated` `tabs.onUpdated` `tabs.query` `windows.onFocusChanged`
borderify	Adds a solid red border to all webpages matching mozilla.org.
chill-out	Show a page action after a period of inactivity. Show cat gifs when the page action is clicked.	`alarms.clearAll` `alarms.create` `alarms.onAlarm` `pageAction.hide` `pageAction.onClicked` `pageAction.show` `tabs.get` `tabs.onActivated` `tabs.onUpdated` `tabs.query` `tabs.update`
commands	Demonstrates using the commands API to set up a keyboard shortcut. The shortcut created is accessed using Ctrl+Shift+Y (Command+Shift+Y on a Mac).	`commands.getAll` `commands.onCommand`
context-menu-copy-link-with-types	Add a context menu option to links to copy the link to the clipboard, as plain text and as a link in rich HTML.	`contextMenus.create` `contextMenus.onClicked` `tabs.executeScript`
context-menu-demo	Demonstrates adding and manipulating context menu items using the contextMenus API.	`contextMenus.create` `contextMenus.onClicked` `contextMenus.remove` `contextMenus.update` `i18n.getMessage` `runtime.lastError` `tabs.executeScript`
contextual-identities	List, create, and remove contextual identities.	`contextualIdentities.query` `tabs.create` `tabs.query` `tabs.remove`
cookie-bg-picker	Allows the user to customize the background color and tiled pattern on sites the visit, and also saves their preferences via a cookie, reapplying them whenever they revisit a site they previously customized.	`cookies.get` `cookies.onChanged` `cookies.remove` `cookies.set` `extension.getURL` `runtime.onMessage` `tabs.onActivated` `tabs.onUpdated` `tabs.query` `tabs.sendMessage`
dynamic-theme	Dynamic theme example	`alarms.create` `alarms.onAlarm` `theme.update`
embedded-webextension-bootstrapped	Demonstrates how to use an embedded WebExtension to port from a bootstrapped extension.	`runtime.onMessage` `runtime.sendMessage` `storage.local`
embedded-webextension-sdk	Demonstrates how to use an embedded WebExtension to port from an SDK-based add-on.	`notifications.create` `runtime.connect` `runtime.onConnect` `runtime.onMessage` `runtime.sendMessage` `storage.local`
emoji-substitution	Replaces words with emojis.
eslint-example	Demonstrates how to configure an extension with eslint.
favourite-colour	An example options page, letting you store your favourite colour.	`browserAction.onClicked` `runtime.openOptionsPage` `storage.sync`
firefox-code-search	Demonstrates how to use the omnibox API.	`omnibox.onInputChanged` `omnibox.onInputEntered` `omnibox.setDefaultSuggestion` `tabs.create` `tabs.update`
forget-it	Demonstrates how to use the browsingData API.	`browserAction.onClicked` `browsingData.remove` `notifications.create` `storage.local`
google-userinfo	Demonstrates how to use the identity API.	`browserAction.onClicked` `identity.getRedirectURL` `identity.launchWebAuthFlow` `notifications.create`
history-deleter	History API demo: deletes history items for a given domain	`history.deleteUrl` `history.search` `pageAction.show` `tabs.onUpdated` `tabs.query`
imagify	Using a sidebar, illustrates the use of file picker and drag and drop. A content script replaces the current page content with the chosen image.	`runtime.onMessage` `tabs.executeScript` `tabs.query` `tabs.sendMessage`
latest-download	Shows the last downloaded item, and lets you open or delete it.	`downloads.erase` `downloads.getFileIcon` `downloads.open` `downloads.removeFile` `downloads.search`
list-cookies	This extensions list the cookies in the active tab.	`cookies.getAll` `tabs.query`
mocha-client-tests	This example shows two methods of testing an extension: running tests from within the extension, and running tests from the command line using Karma	`runtime.sendMessage`
native-messaging	Example of native messaging, including a Python application and an extension which exchanges messages with it.	`browserAction.onClicked` `runtime.connectNative`
navigation-stats	Demonstration of the webNavigation API, showing basic stats about which pages you've visited.	`storage.local` `webNavigation.onCompleted`
notify-link-clicks-i18n	Shows a localized notification when the user clicks on links.	`extension.getURL` `i18n.getMessage` `notifications.create` `runtime.onMessage` `runtime.sendMessage`
open-my-page-button	Adds a browser action icon to the toolbar. When the browser action is clicked, the add-on opens a page that was packaged with it.	`browserAction.onClicked` `tabs.create`
page-to-extension-messaging	Demonstrates how a web page and a content script can exchange messages. Visit https://mdn.github.io/webextensions-examples/content-script-page-script-messaging.html for the demo.
permissions	Demonstrates optional permissions using the permissions API.	`browserAction.onClicked` `permissions.getAll` `permissions.remove` `permissions.request` `runtime.getURL` `tabs.create`
proxy-blocker	Uses the proxy API to block requests to specific hosts.	`extension.getURL` `proxy.onProxyError` `proxy.registerProxyScript` `runtime.onMessage` `runtime.sendMessage` `storage.local` `storage.onChanged`
quicknote	Allows the user to make quick notes by clicking a button and entering text into the resulting popup. The notes are saved in storage.	`storage.local`
react-es6-popup	This is an example of creating a browser action popup UI in React and ES6 JavaScript.
selection-to-clipboard	Demonstrates how to write to the clipboard from a content script
stored-credentials	Performs basic authentication by supplying stored credentials.	`storage.local` `webRequest.onAuthRequired` `webRequest.onCompleted` `webRequest.onErrorOccurred`
tabs-tabs-tabs	Demonstrates tab manipulation: opening, closing, moving, zooming tabs.	`tabs.create` `tabs.duplicate` `tabs.getZoom` `tabs.highlight` `tabs.move` `tabs.onMoved` `tabs.onRemoved` `tabs.query` `tabs.reload` `tabs.remove` `tabs.setZoom`
theme-switcher	An example of how to use the management API for themes.	`management.getAll` `management.setEnabled`
themes	A collection of themes illustrating: weta_fade: a basic theme employing a single image specified in `headerURL:`. weta_fade_chrome: the weta_fade theme implemented with Chrome compatible manifest keys. weta_tiled: a theme using a tiled image. weta_mirror: a theme using multiple images and aligning those images in the header. animated: use of an animated PNG.
top-sites	Demonstration of the topSites API.	`topSites.get`
user-agent-rewriter	Demonstrates using the webRequest API to rewrite the User-Agent HTTP header.	`extension.getBackgroundPage` `webRequest.onBeforeSendHeaders`
webpack-modules	Demonstrates how to use webpack to package npm modules in an extension.	`runtime.onMessage` `runtime.sendMessage`
window-manipulator	Demonstrates how to manipulate windows: opening, closing, resizing windows.	`windows.create` `windows.getAll` `windows.getCurrent` `windows.remove` `windows.update`

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