[WorldMaker]

In addition to some of the other answers already:

1. The focus on typescript and typings distribution is useful/interesting for the "promise" that all packages in the registry have typings. If you can trust that every package in JSR has types then you avoid/simplify that current cycle of: npm install a package, find out it doesn't have types, try to install a package of the same name with @types/ in front of it, find out it doesn't exist, look for an alternative library with types or write your own types or give up and `declare module "thatpackagename"` any-type it.

2. Just because "most" production websites do bundling doesn't mean that needs to still be the status quo in 2024. Bundling is increasingly a "premature optimization" and you might not need it. It can be worth investigating if your site/app works well enough with just ESM delivered straight to browsers in 2024 versus what you "gain" from bundling. You might be surprised at how well current browsers can load ESM and the optimizations they already do for you. But even if you do still need bundling ESM is a huge advantage over other formats (especially CommonJS) and every current bundler produces better, more optimized output the more ESM you provide. Their outputs also increasingly look like ESM, and if that isn't the current default it is the "soon" default. esbuild in particular (which also backs some of vite's tools and others) has an ESM bundle output that is delightful, isn't yet the default ("soon") but is a simple "format" switch away. Those ESM bundles are great in today's browsers. ESM matters a lot to bundlers, bundlers are increasingly ESM in their internals and output. Browsers are great with ESM. The "web-standard" part is pretty meaningful today and getting stronger.

[wruza]

Where can one read up on [2.]?

[WorldMaker]

I got into some details on how I do light-weight apps (especially during development) without bundling in a nearby comment as well: https://news.ycombinator.com/item?id=39564986

To resummarize: sometimes it is fine to prune and ship node_modules to your web server, you can use import maps to handle "node-style 'bare' imports", and you may only need to "spot bundle" to ESM a single dependent library or two that doesn't ship ESM that will directly work in the browser (which should be a decreasing list).

After that it's a matter of using your browser's Dev Tools to tell you what your performance looks like and where your bottlenecks are. That can tell you a lot to help you determine if you really need to bundle more of your site/app or if you can spot-bundle/adjust an import map for just a specific sub-graph. With HTTP/2 and HTTP/3 the "per-file" "penalty" is a lot less, though still somewhat exists. Even some properly configured HTTP/1.1 servers it is not always as bad as history tells us it was (properly configured HTTP/1.1 did support some connection sharing). About the only remaining thing a bundle might buy you on HTTP/2+ is maybe better behavior with compression on the bundle as a single whole, but even that isn't a given because Brotli's dictionary was designed to work at the whole connection level and that's often the default compression in HTTP/2+. But again, your conditions may vary based on your real code and the specific servers and browsers you need to support, so leverage your browser Dev Tools and check the real numbers.