i wish it was that easy. i keep trying to default to esm on node projects but the ecosystem is not there yet, at least in the context of server side nodejs stuff.
It's one reason to consider a switch to Deno or Bun, but at least to maybe at least check JSR before NPM these days. The ecosystem for server-side ESM exists and is growing at a rapid pace, but it's sometimes hard to separate the active maintained npm packages from the legacy ones in the server-side ecosystem. (Browser ecosystem is definitely more ESM hungry.)
That said with "type": "module" in my own package.json files, I've so far never had a problem importing legacy CJS npm packages into ESM, other than the Types are more likely to be wrong (because packages that only publish CJS are more likely to also not publish their own types) or at least inaccurate for the current import approach (returning only "synthetic default" instead of individual exports, for example). That's a bunch of papercuts having to attempt multiple imports until you understand what shape Node is giving you of that CJS import, but after those papercuts I feel like interop is generally smooth sailing in today's Node.
Interesting. Every example that I've seen of React SSR is all natively in ESM, but I've mostly only glanced at the big ones (Astro/Next/Nuxt). I'm sure that there are a lot of paths that aren't as well paved given how diverse the React SSR space currently is (there are way too many competing options), and how simple you want to try to keep your SSR (a lot of those options are just so complex today, which presumably is why there are so many competing options, everyone has a different idea of how complex to make the whole thing).
(My own .tsx based view library doesn't yet have official SSR support, but I do all my testing in ESM in the built-in Node test runner `node --test` so I don't see any complications in doing .tsx on the "server-side", because that is how I'm testing everything already, I just haven't entirely figured out my "hydration" or "islands" or "stamps" approach so I don't officially support SSR yet. It's on the roadmap and I've made small bits of progress towards it, just need to solve it and haven't had the time/priority.)
