As a JS dev, the situation annoys me too, but I'll say at least it's a lot better than it used to be. We've gone from "manually clobbering together 30 different libraries to make an app" to "choosing one of 3-5 major frameworks".
Yes, those frameworks themselves still have hundreds of sub-dependencies, but usually they're managed by the upstream framework maintainers and upgraded at once. Like you upgrade your Next/Remix/Vite version and then rest of it should take care of itself, with (usually) the framework vendor providing detailed changelogs and code migration tools if necessary. It's not a perfect system but it's a heck of a lot easier than it used to be.
And once you build for production, those hundreds of libs just get tree-shaken and bundled into a few much smaller minified and compressed JS files, and often rehydrated only after the important HTML loads. Done right, it can be better UX than the old SPA days -- at a cost of increased slightly increased mental complexity for developers, but not much more than having to work full-stack in different languages.
The ecosystem is very slowly maturing. IMHO we're probably post-peak now. The last 5-7 years had a huge explosion of JS frameworks because, well, that's the language of the web, and we saw a ton of startup activity. But now that the industry is moving towards AI instead, the web is no longer cool, and probably we'll see a lot less competition/innovation and more consolidation/stagnation. I doubt many of these frameworks will survive long term. My personal guess (only) is that we'll probably only be left with Next and Vite(*) after a few years, with the others fading into history the way Ember, Backbone, Angular, etc. did.
> At what point would any of these become deprecated?
Probably 2-4 years, if history is any indication. They just get less popular and less maintained over time, but there'll always be a long tail of older unmaintained projects running on life support with vulnerable versions, etc. But most projects will move on. In my career as a web dev, I've never seen production frontend code last more than a couple years without drastic changes anyway, so I doubt it really matters. Good excuse for the next generation to rewrite everything from scratch for the nth time, lol. Management's visions and priorities rarely last that long to begin with, so it all just kinda works out... shrug.
I wouldn't build a time capsule in JS, but for websites that by their nature are ephemeral... sure, why not?
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* Vite is just a simple frontend processor and bundler: https://vitejs.dev/guide/features.html
It includes things like TypeScript, JSX, hot module replacement... etc., that used to be a bunch of separate libs. It's heavier than vanilla JS, but much lighter than Next.js. Great for simple SPAs, but if you need more batteries included, Next can get you (much) further before you start having to add in more third-party packages again.
Think of these like a Venn diagram. Vite is a small circle that has a lot of overlap with Next's much bigger circle.