The clipboard extension works for online html5 games. It cannot bypass limitations imposed by the web platforms though:
- Your game needs to be in a Secure Context
- If your game is embedded into another website (e.g. liluo or itch.io), that site must explicitly allow clipboard access to the game in their IFrame Permission Policies.
If you cannot read the clipboard, you must either be using an old version of the extension, or not meeting one of the above criteria imposed by the web platform on clipboard access.