Easy Passwords is based on the Add-on SDK and runs in Firefox. However, people need access to their passwords in all kinds of environments, so I created an online version of the password generator. The next step was porting Easy Passwords to Chrome and Opera. And while at it, I wanted to see whether that port will work in Firefox via Web Extensions. After all, eventually the switch to Web Extensions will have to be done.

Add-on SDK to Chrome APIs

The goal was using the same codebase for all variants of the extension. Most of the logic is contained in HTML files anyway, so it wouldn’t have to be changed. As to the remaining code, it should just work with some fairly minimal implementation of the SDK APIs on top of the Chrome APIs. Why not the other way round? Well, I consider the APIs provided by the Add-on SDK much cleaner and easier to use.

It turned out that Easy Passwords used twelve SDK modules, many of these could be implemented in a trivial way however. For example, the timers module merely exports functions that are defined anyway (unlike SDK extensions, Chrome extensions run in a window context).

There were a few conceptual differences however. For example, Chrome extensions don’t support modularization — all background scripts execute in a single shared scope of the background page. Luckily, browserify solves this problem nicely by compiling all the various modules into a single background.js script while giving each one its own scope.

The other issue is configuration: Chrome doesn’t generate settings UI automatically the way simple-prefs module does it. No way around creating a special page for the two settings. Getting automatic SDK-style localization of HTML pages on the other hand was only a matter of a few lines (Chrome makes it a bit more complicated by disallowing dashes in message names).

A tricky issue was unifying the way scripts are attached to HTML pages. With the Add-on SDK these are content scripts which are defined in the JavaScript code — otherwise they wouldn’t be able to communicate to the extension. In Chrome you use regular

https://palant.de/2016/05/02/adventures-porting-easy-passwords-to-chrome-and-back-to-firefox