Return an exit code on "unload"

[oscarotero]

Hi.
I have a function that execute some stuff. And I want to return different exit codes, depending on the result of this execution. Something like this:

const success = await run();
Deno.exit(success ? 0 : 1);

Sometimes is impossible to know when run() finished (because there may be async functions that don't return a promise), so Deno.exit() can break the execution of some things inside run(). To prevent that, I fixed it with this code:

const success = await run();
window.addEventListener("unload", () => Deno.exit(success ? 0 : 1));

This ensures that only after finish all process, subprocess, etc inside run(), the proper exit code is returned.

After upgrading to Deno 1.7 I'm getting the following error: error: Uncaught RangeError: Maximum call stack size exceeded. I guess this is because #9088, so Deno.exit() dispatches unload event that executed Deno.exit() that dispatches unload and so on.

To prevent this, I think unload should be triggered only once. Or if there's any other way to set an exit code without using Deno.exit(), that would be fine too.

[ghost]

The unload event should only be fired once, I think that's a bug.

[kitsonk]

It should only fire once. We should hold on to a global reference for the event when it is raised and not raise it again if present.