How to call async methods on tab/window close?

[Wizzel1]

So I am trying to set up listeners for browser.tabs.onRemoved and browser.windows.onRemoved in my background script.

These listeners need to be async because I am trying to perform a database operation and set local storage properties.

Something like this:

browser.windows.onRemoved.addListener(async (windowId) => {
  const uploaderTab = await extensionStorage.getItem('uploaderTab');
  if (windowId === uploaderTab?.windowId) {
    console.log('Closed the uploader window', windowId); //this logs every time
    await resetTasks(); // sometimes has no effect.
    await extensionStorage.removeItem('uploaderTabId');
    await extensionStorage.removeItem('autoRunUploader');
   console.log("always gets logged");
  }
});

but that isn't stable. Sometimes it works, sometimes it doesn't. The resetTasks() methods runs a supabase query.

Am I doing something wrong or is there a more reliable way to do that?

I also tried everything in this SO post with the same result:
https://stackoverflow.com/a/70802055/10847224

[aklinker1]

Code you shared looks fine. Consider adding a mutex to make sure your logic isn't being ran in multiple times in parallel, but closing windows should happen rare enough this isn't contributing to your problem.

import { Mutex } from 'async-mutex';

const mutex = new Mutex();
browser.windows.onRemoved.addListener((windowId) => mutex.runExclusive(() => {
  // your logic here
}));

Otherwise, it seems to me like resetTasks could be problematic, but I don't know what it looks like. If "Closed the uploader window" and "always gets logged" are always logged, then you are calling resetTasks correctly, which is why I think that function is broken.

[aklinker1]

I saw on discord you're seeing this error message:

A listener indicated an asynchronous response by returning true, but the message channel closed before a response was received

Are you trying to send a message in resetTasks?

[Wizzel1]

I saw on discord you're seeing this error message:

A listener indicated an asynchronous response by returning true, but the message channel closed before a response was received

Are you trying to send a message in resetTasks?

No, for some reason that message didn't came up again.

Regarding the initial post: You are right, apparently this didn't have to do anything with the callback but rather that the supabase client didn't have a valid session. Its really annoying that supabase doesn't throw an error in that case...

I will do some further testing and let you know if I encounter the same problem again. Sorry for the dumb questions...

[Wizzel1]

So my method works now but there is something else I noticed. The onRemove listeners don't fire when the entire browser is closed (or the last tab of a browser). I guess this is expected but do you know of any trick that could help me with this?

[aklinker1]

There are on suspend and startup listeners you can add to clear your storage

• https://developer.chrome.com/docs/extensions/reference/api/runtime#event-onStartup
• https://developer.chrome.com/docs/extensions/reference/api/runtime#event-onSuspend