Code from a project billed as “the future of developing add-ons” in Firefox will debut in early 2016.

The code will let extensions written for Google’s growing Chrome run, supposedly unchanged, in Firefox.

The WebExtensions API, announced in August and currently in alpha, is expected to see daylight in March 2016, with Firefox 45, Mozilla has said.

Mozilla’s browser will see “full support” for APIs providing alarms, contextMenus, pageAction and browserAction.

Also supported will be APIs for bookmarks, cookies, extensions, runtime, storage and tabs - among other browser staples.

A beta is planned in Firefox 47 with the first stable release scheduled for Firefox 48.

Also in the works is the ability for developers to upload their extensions for testing to addons.mozilla.org, in time for Firefox 44.

WebExtensions API is a Blink-compatible API and the idea is that extensions written for Chrome and Opera that use this architecture will run with few changes.

Blink is a Chromium project, with a Blink-in-Javascript mechanism that lets you implement the Document Object Model (DOM) using Javascript rather than on a browser-by-browser basis using C++.

Mozilla has hailed Blink as a “modern and Javascript centric API” whose benefits include “supporting multiple process browsers by default and mitigating the risk of misbehaving add-ons and malware”.

The idea is that WebExtensions behave like other Firefox add-ons, are signed by Mozilla, and are discoverable through addons.mozilla.org or through the developer’s website.

“With this API, extension developers should be able to make the same extension available on Firefox and Chrome with a minimal number of changes to repackage for each platform,” Mozilla said.

You could call it write-once-run-anywhere for the Javascript, not the Java, generation.

It comes as use of Chrome shot up in 2015, becoming the choice not just of developers but of the enterprise - behind Microsot's Internet Explorer - while Firefox fell from one quarter market share to just over 10 per cent. ®