[gorhill]

For an extension to be entirely declarative, it must package all the scripts to inject anywhere, the scripting.registerContentScript API doesn't allow injecting code as string[1], the content scripts must be part of the package.[2]

There is userScripts API which allows injecting code as string, but it's impractical as in Chromium-based browsers this requires extra steps by the user to enable the API.[3] In Firefox, the documentation for this API has the following note[4]:

> When using Manifest V3 or higher, use scripting.registerContentScripts() to register scripts

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[1] https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...

[2] https://github.com/uBlockOrigin/uBOL-home/tree/main/chromium...

[3] https://developer.chrome.com/docs/extensions/reference/userS... ("Availability Pending")

[4] https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...