[BUG] MediaSession API doesn't seem to work about violentmonkey HOT 9 CLOSED

Works for me in Chrome, so I guess Firefox doesn't implement it fully.

from violentmonkey.

It works fine in Firefox, just not in a userscript. I've tested it in console and I could also test it in a webextension. Is there some reason why it would work elsewhere but not in a userscript?

from violentmonkey.

I was wrong, it's the same in Chrome. I was confused by the Play button being ignored in Firefox (I had to restart it).

So apparently youtube overrides your handler and you need to run your code later?

from violentmonkey.

In other words, this is how the API is designed and I don't see anything we can do about it.

from violentmonkey.

Honestly I don't think it's that. That was one of the things I thought might be the issue in my troubleshooting, so I also tried this pattern:

let addListener = () => navigator.mediaSession.setActionHandler("play", function () {
  console.log("GREETINGS;");
});

addListener();

setTimeout(addListener, 10000);

As well as testing document-idle and document-end for @run-at.

I'm not sure youtube is setting an action handler at all. Firefox natively handles media keys on all sites. It's part of the basic implementation and toggled by the pref media.hardwaremediakeys.enabled. So the fact that media keys work on youtube doesn't mean youtube is handling them; Firefox just handles media keys for all media elements.

from violentmonkey.

But your new code works for me and I don't see any other theoretically possible explanation.

from violentmonkey.

In that case I suppose you're right. It doesn't work for me, but maybe I need to try other asynchronous methods. It feels like youtube's loading is somehow hampered by the timeout, even though it should not be blocking. Maybe the script is causing youtube to set its action handler later than usual.

I'll see what else I can do. Thanks for testing.

I suppose I could set my handlers and then no-op the setActionHandler method.

from violentmonkey.

Judging by the documentation for setActionHandler, this is how it's designed to work. It's not like addEventListener, but like elem.onclick = foo which overwrites the old listener.

You'll have to implement cascading manually, e.g.:

const playCallbacks = new Set();
const M = navigator.mediaSession;
M.setActionHandler("play", info => {
  console.log("GREETINGS;");
  for (const fn of playCallbacks) fn(info); // IDK about try-catch handling
});
M.setActionHandler = new Proxy(M.setActionHandler, {
  apply(fn, thisArg, args) {
    if (args[0] === 'play') playCallbacks.add(args[1]);
    else Reflect.apply(fn, thisArg, args);
  }
});

from violentmonkey.

Thanks! Yeah that makes sense. I won't need cascading since I just want to override nexttrack and previoustrack (youtube's shuffling gets stuck in loops sometimes), but I can do that too with a proxy. By breaking on setActionHandler I found that youtube actually sets the action handlers 3+ times, starting early and continuously attempting it at least 2 times. Kinda weird but I guess that explains it.

Seems to work using this approach: https://github.com/aminomancer/userscripts/blob/main/betterYouTubeMediaKeyHandlers.user.js

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