According to spec [1] it is allowed to change properties within the MediaMetadata rather than assigning a new instance.
Using a Proxy object lets us detect property assignments within the object. Conveniently, it still reports instanceof as being the original object.
[1] https://www.w3.org/TR/mediasession/#the-mediametadata-interface (last sentence)
This fixes VKontakte player not updating metadata when changing tracks. Thanks @IlyaBizyaev for investigating.
YouTube, vimeo, media session example (who all set new metadata instance when they change) still get their metadata propagated correctly
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AFAICT (take with a grain of salt, I'm a JS n00b) this doesn't catch something like this:
let a = {};
navigator.mediaSession.metadata = a;
a["foo"] = "bar";And behaves weirdly if you do:
let a = navigator.mediaSession.metadata; navigator.mediaSession.metadata = null; a["foo"] = "bar";
| extension/content-script.js | ||
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| 716 | That appears to work fine here | |
this doesn't catch something like this
Yeah it doesn't. I thought I could "monitor" an Object but the caller actually has to use the Proxy for it to detect anything :/
Any ideas? :)
| extension/content-script.js | ||
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| 716 | Hmm this didn't work back when I implemented this originally when chrome added support for MediaMetadata | |
Other than using an interval timer to sync regularly, not really. At least the first case seems impossible to fix.
The second case could be fixed though by navigator.mediaSession.metadata === this or something like that...
Maybe if I overwrote MediaMetadata with a Proxy object already, then the website would never have a separate Object to work with.. hmm