The Program ID

The Program ID is a unique identifier for your add-on. When you package your add-on for distribution using cfx xpi, it will become the ID field in the add-on's Install Manifest.

The ID is used for a variety of purposes. For example: uses it to distinguish between new add-ons and updates to existing add-ons, and the simple-storage module uses it to figure out which stored data belongs to which add-on.

It is read from the id key in your add-on's package.json file. cfx init does not create this key, so if you don't set it yourself, the first time you execute cfx run or cfx xpi, then cfx will create an ID for you, and will show a message like this:

  No 'id' in package.json: creating a new ID for you.
  package.json modified: please re-run 'cfx run'

The ID generated by cfx in this way is a randomly-generated string, but you can define your own ID by editing the package.json file directly. In particular, you can use the format described in the Install Manifest documentation. However, you can't use the GUID-style format.