- As the Firefox extension model still requires a browser restart for many changes, make sure you at least don't have to repeat the messy part of packaging your xpi and installing it again over and over again (unless that is the part you are debugging at the moment).
Reading the page on how extensions are installed on your operating system, replace the directory with your extension's guid with either a symlink to the directory where you develop your extension, or a file containing the path to it (if, say, you work on Windows with some file system that doesn't support symbolic links). Now you can edit your code, restart Firefox, and see the effect immediately without the extra steps of building an xpi and installing it every time you change something.
(If your extension uses the more elaborate jar double zipping build procedure, my suggestion is "don't do that while developing", as doing more, invariable also takes more time and effort.) - Install the QuickRestart extension, as Firefox developers don't give you access to the crucial feature of restarting your session via keyboard hot key.
- Check out the File menu and learn the hot key.
- Some things can be updated without a browser restart, even in Firefox! (*) Set your development profile's about:config preference nglayout.debug.disable_xul_cache = true. <= this entire page is worth a read-through
- Maybe you're poking around with things in an overlay in browser chrome and really just wish you could have a read-eval-print console into it, kind of like Firebug's. That's what MozRepl does. Install it, and now you can telnet or netcat into your browser session (from a terminal window, or maybe emacs), after focusing which window you want to have a prompt in.
- If you are hacking on Greasemonkey specifically, and, say, poking with any of the stuff concerning gm_scripts and what is stored there, I suggest you cd into your gm_scripts directory, run git init, git add * and git commit -a -m 'Something descriptive' so you can revert to a prior state effortlessly with a git reset --hard before restarting, when your code changed something and you want to restart from a known earlier state.
That's all for today. Doubtlessly there are tons of other things that slim up the dev cycle. Feel free to post, or better still, link to other useful things to do. The docs at MDC are unfortunately too ill organized to easily strike gold there, so web pages that aggregate the nuggets are particularly valuable resources.
(*) Mozilla developers are hard at work making future extensions based on their (recently rebooted) Jetpack (SDK) project able to update without a browser restart, just like Greasemonkey scripts or Google Chrome extensions can. Any year now.