Ah, you've stumbled on the event queuing behaviour of hyperscript:

If a triggering event is received while an event handler is executing, you can specify various behaviours:

https://hyperscript.org/features/on/#queueing

The default is queue last, which will queue the last event and trigger the event handler again once it completes. I agree that is wrong in this case, and so it should specify `queue none` in the handler. I will update the code.

Thank you for taking a close look at the example!