Comment by zamadatix | Hacker News Reader

Comment by zamadatix | Hacker News Reader

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Any MV3 issue could probably be summed up as "MV3 isn't so bad, just the implementation in Chrome" where Chrome defines MV3 (as it's not a W3C standard) and ships it as such.

That said,

> Chromium design decision that extensions cannot block browser initialization

It's not "browser initialization" that was blocked, it was blocking network requests for pages until they were processed by all components in the chain. Notably, this could never apply applied to the browser or its internal pages itself.

> It was also true with MV2.

With MV2 you used the blocking version of https://developer.chrome.com/docs/extensions/reference/api/w... which no longer works with MV3 extensions in Chrome and then the request had to wait until it was given to and processed by the blocker.

Firefox is a great example about all of the above points: MV3 still supports blockingWebRequest there, so it gets the best of both worlds.

> did you know that you can change your User-Agent with uBO lite?

With MV2 you'd use blocking webRequest and chrome.webRequest.onBeforeSendHenders. I'm not sure uBO ever bothered with this before uBO Lite, but it's a bit of a double standard to say "MV2 didn't offer blocking requests, that was a different API which happ

> and then the request had to wait until it was given to and processed by the blocker.

Despite the name, the requests were not blocked until the extension had initialized. The browser could make network requests before that happened with MV2. With MV3, static rulesets and persistent DNR rules are enforced immediately.

> With MV2 you'd use blocking webRequest and chrome.webRequest.onBeforeSendHenders

Of course an extensions could do this, I said uBO lite. DNR made exposing this powerful functionality fast and easy. My point is that MV3 uBO lite has useful features that MV2 uBO does not.

> Despite the name, the requests were not blocked until the extension had initialized. The browser could make network requests before that happened with MV2. With MV3, static rulesets and persistent DNR rules are enforced immediately.

There were several workarounds like suspendTabsUntilReady which helped greatly in this half of the problem. Then it would solidly stay permanently registered too. I'm pretty sure none of these work in Chrome anymore though, it was obvious they never intended these sorts of things to work that way.

Nevertheless, MV3's ability to offer limited filtering on startup does not seem like such a blessing when the other option was to just guarantee full filtering on startup as seen in this change https://bugzilla.mozilla.org/show_bug.cgi?id=1447551

> Of course an extensions could do this, I said uBO lite. DNR made exposing this powerful functionality fast and easy. My point is that MV3 uBO lite has useful features that MV2 uBO does not.

What you said is so, it just might highlight more than what you'd like it to at the same time. That it was missing before had nothing to do with the difficulty or need for MV3. uMatrix had it for a while and Gorhill regretted it because it didn't change things like the user agent JS would report and such, hence he wouldn't port it over. The above filter has the same problems. Great if you just want a normal quality user agent switcher, that it's normal quality is why it was never in the old extension though.

> Nevertheless, MV3's ability to offer limited filtering on startup does not seem like such a blessing when the other option was to just support full filtering on startup

Sure, but as I said, it's a design decision, and nothing to do with MV3. I'm not trying to litigate it one way or the other.

I do think DNR is a good solution, and that request callbacks were a bad idea. That's my opinion - and the counterargument is obvious -- you can't do literally everything you could do in a callback declaratively. That doesn't sway me, I still think it's better!

> Great if you just want a normal quality user agent switcher

It was just a trivial example of using a powerful new feature that uBO doesn't have, not a full featured extension! The fact that it's possible at all is the point, it's cool.

You can definitely do anything that DNR can do with webRequest, nobody can dispute that. The point is that there are things you can do with uBO lite that you can't do with uBO (and vice versa!). It's not a straight downgrade, there are powerful new features.

Again, we really need to separate "MV3 - the theoretical idea" and "MV3 - the actual implementation which ships with Chrome". It's two confusingly different worlds.

Nobody should be swaying you to prefer DNR over webRequest (or vice versa) when other browsers show both can be available options for the extensions you use as makes sense for what they try to do/what type you'd like to install. Continuing to support MV2 power levels of functionality does not mean uBO Lite type extensions would need to stop working the way they do, it means uBO type extensions would continue to work the way they do. I.e. the biggest failure of MV3 is not in lacking anything new whatsoever, it's in forcing the removal of a lot of API options which were useful in the name of ulterior motives.

> You can definitely do anything that DNR can do with webRequest, nobody can dispute that. The point is that there are things you can do with uBO lite that you can't do with uBO (and vice versa!). It's not a straight downgrade, there are powerful new features.

It's like you sold your house for a mobile home but tell the neighbor it's not a straight downgrade because it's red. Great, but why are we praising that instead of painting the house red?

Funnily enough, this morning I ran across another feature I didn't realize was missing in MV3 https://github.com/uBlockOrigin/uBOL-home/discussions/369. Perhaps keeping the functionality to know what was actually blocked to the extension was too powerful.

> the biggest failure of MV3 is not in lacking anything new whatsoever, it's in forcing the removal of a lot of API options which were useful in the name of ulterior motives.

What was the ulterior motive? If it was to break ad blocking, it seems like they did a really terrible job, as MV3 ad blockers work great. That's not me saying that, here is a paper from researchers at Goethe University Frankfurt who tested it:

> Moreover, cross-browser experiments yield comparable outcomes, and visual inspection confirms that MV3 ad blockers work effectively without significant ad flickering or loss of functionality

From: https://arxiv.org/abs/2503.01000

> Funnily enough, this morning I ran across another feature I didn't realize was missing in MV3

I think you could accomplish this by redirecting instead of blocking, then increment a counter in a webRequest callback. There would obviously be a performance cost, as blocking is so cheap and callbacks are expensive...

Regardless, I think it's jarring hearing you call custom DNR rules "painting the house red", a legitimately powerful feature... and then point to a missing counter in the UI as evidence of lacking features!

Anyway, let's leave it there!

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