Elaborate on "long-running code" and "yield to the event loop"?

[rpivo]

I'm curious what "long-running code" would look like, and how this ties into yielding to the event loop? It sounds like, with the normal callback that would be registered with FinalizationRegistry, it operates at the whim of the browser's event loop. The cleanupSome() callback wouldn't, though, and would instead be called right away?

What is a "long-running code" scenario, and how does it factor in here? Maybe this is elaborated somewhere and I missed it.

Thanks for any help understanding this.