Is online
Whether a player is still on the server, say after a Wait.
A Minecraft element (a check) in Players. Needs the Basic plan or higher to go live; building and testing are free.
Example
When a player uses a command → Wait 10 seconds → If Is online → Give an item.
Also called
online, still here, is on, logged in
Works as a data pack?
Yes. A vanilla data pack does this exactly as the plugin does.
What you give it
- Player