Screenshots first because we all love screenshots:

Firefox.html is an experiment, a proof of concept: trying to re-implement the Firefox UI in HTML, as an app (à la B2G).

Screencast & screenshots

Rationale: We are working hard on making HTML fast and rich enough to build a whole operating system (Firefox OS) and a browser (Firefox OS' browser is built in HTML). Firefox Desktop is built in a different way (XUL). With a UI in HTML leveraging the Browser API, we could drop XUL and close the gap between B2G and Firefox Desktop. And eventually be able to render Firefox Desktop with Servo (which will never support XUL). And maybe, one day, host the Firefox UI online (trusted app?).

Current code is ugly (really). It works on Linux, Windows and Mac. The browser supports basic features (tabs, navigation, history, ssl, devtools, search, zoom, …).

The project is split in two modules: the app and the runtime (HTMLRunner) (see below for details).

Setup

1. Clone this repository somewhere on your computer using git clone --recursive https://github.com/paulrouget/firefox.html or the github application;
2. Download HTMLRunner runtime: http://people.mozilla.org/~prouget/htmlrunner/ (package is named firefox-XX.XX);
3. Run HTMLRunner runtime (binary name is firefox);
4. HTMLRunner will ask (only once) the location of the firefox.html directory you cloned in step 1;
5. You should now see the browser running.

Note: If you have cloned without --recursive, you may find out that lib/require.js is empty. To fix this:

git submodule update --init

How to change code

1. Change code in the firefox.html directory
2. Press Ctrl/Cmd-Shift-R to run the new code (doesn't work on Windows. See issue 12)
3. Submit PR :)

The App

Firefox.html is a HTML app (like any B2G app). It is based on the Browser API and works the same way Gaia's browser and system apps work. Even though it includes tags like vbox, hbox, spacer, …, it's all HTML (see layout.css to see how they mimic xul layout).

Current priority is to re-implement the basic features of Firefox Desktop to make Firefox.html a usable browser, and understand what's missing at the platform level for a perfect integration to the OS.

The Runtime

Firefox.html requires a runtime: a special build of Gecko we call "htmlrunner". The runtime code is based on Firefox. See the htmlrunner branch branch on my gecko-dev repository.

It uses a xul:window that loads the Firefox.html app into an iframe. The xul:window is still required to build a native window (draw in title bar, support opening animations, native colors, …). Eventually, I want to kill this window and bring these native features to HTML. This window is nothing but a window with window controls (close, minimize, maximize).