I have been maintaining a Chrome browser extension I wrote for more than a year now and I always get the occasional user asking me if I can make it work with Firefox. And until now I said no, because I use the "world" feature in manifest.json. But I was wrong.
You see, Google is aggressively pushing for manifest version 3, discontinuing support for browser extensions using v2. So my extension was written from the beginning with version 3. In order to load the scripts and CSS files that I needed to run in the context of the page, I used the world:"MAIN" feature. When I tried it with v2, Chrome immediately told me "The 'world' property is restricted to extensions with 'manifest_version' set to 3 or higher." (Or higher. lol) So when I looked for how to use world in Firefox manifest v3 I got a lot of documentation about Xray Vision and how they absolutely refuse to implement the world feature.
I googled, I scoured the web, I read all of Stack Overflow, I even tried LLMs like ChatGPT of Gemini to hilarious results, like Gemini accusing me I want to circumvent the security of the browser. No. There is no simple way of doing the same thing in Manifest v3 on Firefox. Case closed, right? I mean, who even uses Firefox? Less than 2.5% of people on the Internet. And it's a shit browser.
But no, here comes a guy and tells me that he made it work. HOW?! By now you probably guessed it, I left enough hints after all. You just have to use manifest version 2! 'world' is only restricted for version 3 in Chrome browsers!!!
Although now that I am writing this post I see stuff like Manifest V3 updates landed in Firefox 128 so maybe it something that works only recently (the article is from July 2024). Hmm..
I guess there is a silver lining to the fact I refused users for a year now, because I had a year in which I didn't have to deal with the buggy debugger (heh!) in Firefox.
Anyway, if you have the same problem, that's your solution: make a v2 manifest for Firefox and a v3 manifest for Chromium browsers. Or use it in v3 as well, because apparently Firefox changed their minds. And I wrote this blog with such glee that I would help people that had the same problem as me. Ugh!
NO! I will not make it work for Safari!
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