Fourth [LWN.net]

Fourth

Posted Dec 16, 2025 20:57 UTC (Tue) by davecb (subscriber, #1574)
In reply to: Fourth by pizza
Parent article: Mozilla gets a new CEO: Anthony Enzor-DeMeo

Yes, this is called the "modem testing problem"*.

Were I working on Firefox (I'm not), I'd build a mechanism with something like Playwright to download a url and compare the two files, alerting on things that responded differently. Then I'd review the difference and decide if it deserverd to be changed in Firefox.

A customer used to do something quite similar, when they needed their program to work on numerous browsers.

--dave
[https://leaflessca.wordpress.com/2017/01/03/the-modem-tes...

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Fourth

Posted Dec 16, 2025 22:35 UTC (Tue) by pizza (subscriber, #46) [Link] (2 responses)

> Then I'd review the difference and decide if it deserverd to be changed in Firefox.

The answer will _always_ be "we must be bug-for-bug compatible with Chrome"

(Because even if Firefox is "correct", that doesn't change the indisputable fact that it "works just fine" in every other browser)

How to be compatible with Chrome?

Posted Dec 17, 2025 15:32 UTC (Wed) by DemiMarie (subscriber, #164188) [Link] (1 responses)

The question is how to achieve this.

Should Firefox be another Chromium-based browser? Or is there a way to make this work with Gecko?

How to be compatible with Chrome?

Posted Dec 18, 2025 8:56 UTC (Thu) by taladar (subscriber, #68407) [Link]

If they decided to replace Gecko with the same engine every other browser is using they would lose most of their remaining user base. Their one major advantage right now is that they are preventing a total browser engine mono-culture.