Developing Firefox Extensions

1. Create a development profile: 
   
   
   
   You need to install several extensions which may slow down firefox performance. So create a separate development profile using the following steps-
   

   • Open command prompt
   • [Firefox Installation Directory]\firefox.exe -no-remote -P
   • Create a new profile.
   • Start firefox next time with the command: [Firefox Installation Directory]\firefox.exe -no-remote -P [new profile name]

   
   
2. Install some useful extensions: Firebug is the most useful one.
   
   
   
   • Firebug: https://addons.mozilla.org/en-US/firefox/addon/1843/
   • DOM Inspector: https://addons.mozilla.org/en-US/firefox/addon/6622/
   • Extension Developer: https://addons.mozilla.org/en-US/firefox/addon/7434/
3. Set some developer preferences: Type about:config in the address bar. Set or add, if do not already exist, the following properties:
   
   
   
   • javascript.options.showInConsole = true.
   • nglayout.debug.disable_xul_cache = true.
   • browser.dom.window.dump.enabled = true.
   • javascript.options.strict = true.
   • extensions.logging.enabled = true.
   • dom.report_all_js_exceptions = true.

   
   
   
4. Directory structure: Different from usual programming frameworks, Firefox extension has a predefined directory structure for files. The browser will look in specified folder when it needs a file for e.g. installation, preference or visual overlays.
   
   
   
   • For new extension: Use the wizard in http://ted.mielczarek.org/code/mozilla/extensionwiz/. Copy the contents of the generated zip file into [Profile]\extensions\] folder. It is a folder with the name of your desired extension name. Rename this folder name into the extension ID from install.rdf or use some unique name like an e-mail address. Restart firefox. Your add-on should appear in the browser. Check Tools->Add-ons if your extension is listed there.
   • Existing extension: Copy extension into the [Profile]\extensions\] folder. Remember the filename or sub-folder for the extension must be same as the extension ID in install.rdf or a unique name like an e-mail address.