How to match all domain extensions in content script (firefox)?

I need to match all domain extensions for a simple Firefox extension I am writing. For example, I need to the extension to run on:

• https://example.com
• https://example.org
• https://example.net

I do not want the extension to run on anything that isn't the 'example website, e.g.,

• https://water.com
• https://facebook.com
• https://google.com

This is important, in part, so that I do not need to get permission to access data on all website for my extension.

Notes:

• this is not a question about regular expressions matching per se (there appear to be different rules at play here; this is not a duplicate of Regex Match Domain Extension)
• This is not a duplicate of Chrome extension: Run on all google domains and a specific page (does not solve this issue)

from How to match all domain extensions in content script (firefox)?