1. What is an add-on ID?
2. What is a Firefox profile?
3. Extension behavior in Firefox
4. What do I do to ensure I can test my extension?

• storage.managed—identifies data as belonging to the extension by its add-on ID.
• storage.sync—identifies data as belonging to the extension by its add-on ID.
• identity.getRedirectURL—the redirect URL includes the extension's add-on ID.
• Native messaging—the native app identifies extensions that can communicate with it by their add-on ID.
• pkcs11—the PKCS #11 module identifies extensions that can communicate with it by their add-on ID.
• runtime.onMessageExternal—an extension sends messages to another extension using its add-on ID as the address.
• runtime.onConnectExternal—an extension requests a connection with an extension by the other extension's add-on ID.
• browserAction—the saved position of the button is identified as belonging to the extension based on its add-on ID.

An extension can be assigned an add-on ID using themanifest.json filebrowser_specific_settings key.

"browser_specific_settings":{"gecko":{"id":"addon@example.com"}}

If the extension doesn't have an add-on ID defined with thebrowser_specific_settings key, it gets an add-on ID through one of the following:

• If the extension is submitted AMO and signed, it's given an ID when it's signed.
• If the extension is loaded using Load Temporary Add-on inabout:debugging it's assigned a temporary add-on ID.

You'll notice an additional ID in the image above, the Internal UUID. This is a unique identifier given to the extension on installation. It's used to define the storage location for resources included in the extension and identify an extension's data inwindow.localStorage orindexedDB. However, you don't need to know its value. Its use inwindow.localStorage orindexedDB is transparent and to access resources included in the extension you useruntime.getURL, which returns the path to the resources. And, because it's unique to each installation, it doesn't provide an ID that can be relied upon for other purposes.

Data that defines how the user has configured Firefox, along with information generated as they browse the web such as history and cookies, is stored in a special folder, called aprofile. In addition to cookies, the profile holds local storage and other profile related content.

• to make sure an extension can use add-on ID dependent features between reloads, such as local storage or native application communication:

  • set an add-on ID using thebrowser_specific_settings key in the extension'smanifest.json.
  • when using web-ext, make sure you use the same profile.

• to ensure you use the same profile for multiple tests of an extension when using web-ext:

  • optionally, useProfile Manager to create a new Firefox profile.
  • find the path to your new profile or the default Firefox profile by following the instructions inHow do I find my profile?
  • add the Firefox profile path to theweb-ext run command as follows:
    web-ext run --firefox-profile [A PATH TO A FIREFOX PROFILE] --keep-profile-changes

• to preservestorage.local data, access towindow.localStorage orindexedDB data when removing a temporary add-on (such as between browser restarts):

  • go toabout:config and set both
    extensions.webextensions.keepStorageOnUninstall and
    extensions.webextensions.keepUuidOnUninstall totrue.

• to test restart behavior:

  • set an add-on ID using thebrowser_specific_settings key in the extension'smanifest.json.
  • install theNightly orDeveloper editions of Firefox. Note: You can also useunbranded Beta and Release builds.
  • go toabout:config and setxpinstall.signatures.required tofalse.
  • package your extension into a ZIP fileusing web-ext or byzipping it manually.
  • install your extension using Install Add-on From File in the Add-on manager (about:addons).
    Note: Remember you'll need to reload your extension each time you change it.
    Note: If you don't set the add-on ID, when you load the extension you get an error like this:
    
    with a matching error in the browser console.

  

Tags: add-on beginner development extensions how-to intermediate testing webextensions 

Contributors: freaktechnik Rob--W rebloor tophf Dietrich 

Last update: rebloor Mar 18, 2019