SpyreStudios

Web Design and Development Magazine

  • Design
  • Showcase
  • Inspirational
  • Tutorials
  • CSS
  • Resources
  • Tools
  • UX
  • More
    • Mobile
    • Usability
    • HTML5
    • Business
    • Freebies
    • Giveaway
    • About SpyreStudios
    • Advertise On SpyreStudios
    • Get In Touch With Us

How to Build a Firefox Extension

February 12, 2018 by Alex Fox

Firefox may not be as popular as Google Chrome, but with the release of the super fast Firefox Quantum, it’s likely that the user base will grow in the future. To take advantage of what’s sure to be a growing population of users, you can build a Firefox extension (“add-ons” in Firefox parlance). This actually follows many of the same steps as building an extension for Google Chrome, which we covered in a previous post. This guide will take you through the process to build a super-simple Firefox extension, much in the same style as our Google Chrome extension.

When clicked, our extension will pop up a small web page that displays a little content. While this function on its own is pretty minimal, it will give you the basic information you need to start building your own extensions. If you want to explore deeper, you can check out the official Firefox extension documentation at the Mozilla Developer Network. There’s a lot there, and web developers will recognize that MDN is a reliable source for technical web design information.

Build a Firefox Extension: Hello World

Before we do anything, we’ll need to create a new folder to house all of our extensions parts. For this exercise, we will call our extension’s folder “Hello World” and create a folder with that same name. You can use that name, or any name you like. The name of your extension will actually be specified in a separate file.

Below, we can see the files that our folder will eventually contain.

build a firefox extension directory

As in our Google Chrome extension , the primary files are our manifest.json and our popup.html. The manifest tells the browser all about our extension. It’s where all the critical information is maintained, like name, description, version, and files used in the extension. We also have some icons in a folder, with a 16 pixel and 32 pixel version. Those icon locations will be specified and loaded by our manifest. The manifest we’re using appears as below.

{
    "description": "Demo toolbar functionality",
    "manifest_version": 2,
    "name": "Hello World!", 
    "version": "1.0a",
       
    "browser_action": {
        "browser_style": true,
        "default_popup": "popup.html",
        "default_icon": {
         	"16": "icons/page-16.png",
         	"32": "icons/page-32.png"
         }
    }

}

Let’s break down what’s going on in this manifest file.

  • description: a short description of the extension that will display in the add-ons window when the extension is loaded
  • manifest_version: a required statement for the most up-to-date version of the manifest framework
  • name: the name the extension will use when loaded in to Firefox
  • version: the version of the extension
  • browser_action: for our simple extension, this section of the manifest describes the entirely of the extensions function. A browser action extension places a clickable icon in Firefox’s toolbar. The user can click on the icon to interact with your extension and run its contents. In this case, our icon will simple load our popup.html when clicked on.
    • browser_style: allows the extension to follow the styling of the browser toolbar, making it fit in better with user extension
    • default_popup: specifies the file that will load when the extension is clicked
    • default_icon: specifies the location of the icon files within the extension’s directory. We’ve included both a 16 pixel and 32 pixel version with our extension to accommodate high-density displays.

Other sections of the manifest exist, and can expand the extensions functionality greatly, including running scripts. To learn more about those, check out Mozilla’s documentation on content scripts.

Running HTML with a Firefox Extension

Now that we’ve built the core of our extension, we can deal with the HTML we’re running. Here’s the source code for our popup.html file.

build a firefox extension HTML file

Obviously, this represents just about the bare minimum for an HTML page. You can get much more complicated, of course. If you want to run scripts, however, you can’t include them in your HTML. Thanks to security rules for the spec, you’ll need to load them via content scripts in your manifest file.

Temporarily Loading your Firefox Extension

For debugging and testing, you can temporarily load your Firefox extension in to your installation of Firefox. The extension will only stay loaded until you restart Firefox. Obviously, this is not how users are supposed to install extensions: publishing Firefox extensions is an entirely separate process.

1. Type “about:debugging” in to your Firefox address bar

build a firefox extension

2. Check the box next to “Enable add-on debugging”

build a firefox extension

3. Click the “Load Temporary Add-on” button

build a firefox extension

4. Select the manifest.json file in your extension’s directory

build a firefox extension

5. If you have any errors in your extension, Firefox will alert you. Once everything is good, your extension will be loaded!

build a firefox extension

 

Conclusion

Building a simple Firefox extension is much like building a simple Chrome extension. If you can build one, much of your work could easily transfer to another. Of course, there are implementations differences, but the core frameworks are largely similar. If you want to learn more about what you can do with extensions, take a look at Mozilla’s official documentation for Firefox extension.

You might also like the following posts:

30 Tutorials for Developing HTML5 Web Browser Games

How to Change Default Text Wrapping with HTML and CSS

Tricks to Overcome Common Development Problems

Icons made by Flat Icons from www.flaticon.com is licensed by CC 3.0 BY

Filed Under: Tutorial Tagged With: extension, tutorial

Recent Posts

  • 31 Fresh Design Elements for Spring and Easter
  • 10 Templates for Music Concert Flyers
  • How to Build a Web Scraper Using Node.js
  • Best PHP Books, Courses and Tutorials in 2022
  • How to Get Your First Web Design Client

Archives

  • April 2022
  • March 2022
  • February 2022
  • January 2022
  • December 2021
  • November 2021
  • October 2021
  • September 2021
  • August 2021
  • July 2021
  • June 2021
  • May 2021
  • April 2021
  • March 2021
  • February 2021
  • January 2021
  • December 2020
  • November 2020
  • October 2020
  • September 2020
  • August 2020
  • July 2020
  • June 2020
  • May 2020
  • April 2020
  • March 2020
  • February 2020
  • January 2020
  • December 2019
  • November 2019
  • October 2019
  • September 2019
  • August 2019
  • July 2019
  • June 2019
  • May 2019
  • April 2019
  • March 2019
  • February 2019
  • January 2019
  • December 2018
  • November 2018
  • October 2018
  • September 2018
  • August 2018
  • July 2018
  • June 2018
  • May 2018
  • April 2018
  • March 2018
  • February 2018
  • January 2018
  • December 2017
  • November 2017
  • October 2017
  • September 2017
  • August 2017
  • July 2017
  • June 2017
  • May 2017
  • April 2017
  • March 2017
  • February 2017
  • January 2017
  • December 2016
  • November 2016
  • October 2016
  • September 2016
  • August 2016
  • July 2016
  • June 2016
  • May 2016
  • April 2016
  • March 2016
  • February 2016
  • January 2016
  • December 2015
  • November 2015
  • October 2015
  • September 2015
  • August 2015
  • July 2015
  • June 2015
  • May 2015
  • April 2015
  • March 2015
  • February 2015
  • January 2015
  • December 2014
  • November 2014
  • October 2014
  • September 2014
  • August 2014
  • July 2014
  • June 2014
  • May 2014
  • April 2014
  • March 2014
  • February 2014
  • January 2014
  • December 2013
  • November 2013
  • October 2013
  • September 2013
  • August 2013
  • July 2013
  • June 2013
  • May 2013
  • April 2013
  • March 2013
  • February 2013
  • January 2013
  • December 2012
  • November 2012
  • October 2012
  • September 2012
  • August 2012
  • July 2012
  • June 2012
  • May 2012
  • April 2012
  • March 2012
  • February 2012
  • January 2012
  • December 2011
  • November 2011
  • October 2011
  • September 2011
  • August 2011
  • July 2011
  • June 2011
  • May 2011
  • April 2011
  • March 2011
  • February 2011
  • January 2011
  • December 2010
  • November 2010
  • October 2010
  • September 2010
  • August 2010
  • July 2010
  • June 2010
  • May 2010
  • April 2010
  • March 2010
  • February 2010
  • January 2010
  • December 2009
  • November 2009
  • October 2009
  • September 2009
  • August 2009
  • July 2009
  • June 2009
  • May 2009
  • April 2009
  • March 2009
  • February 2009
  • January 2009
  • December 2008
  • November 2008
  • October 2008
  • May 2008
  • April 2008

Categories

  • Accessibility
  • Android
  • Apps
  • Art
  • Article
  • Blogging
  • Books
  • Bootstrap
  • Business
  • CSS
  • Design
  • Development
  • Ecommerce
  • Fireworks
  • Flash
  • Freebies
  • Freelance
  • General
  • Giveaway
  • Graphic Design
  • HTML5
  • Icons
  • Illustrator
  • InDesign
  • Infographics
  • Inspirational
  • Interview
  • Jobs
  • jQuery
  • Learning
  • Logos
  • Matrix
  • Minimalism
  • Mobile
  • Motion Graphics
  • Music
  • News
  • Photoshop
  • PHP
  • Promoted
  • Rails
  • Resources
  • Showcase
  • Tools
  • Tutorial
  • Twitter
  • Typography
  • Uncategorized
  • Usability
  • UX
  • Wallpapers
  • Wireframing
  • WordPress
  • Work

Meta

  • Log in
  • Entries feed
  • Comments feed
  • WordPress.org

SpyreStudios © 2022