[wwwigham]

I think this is funny, since esm being "native" on browsers doesn't really matter until you can convince devs they don't actually need to use a bundler. So long as you're using a bundler, the browser's runtime doesn't really matter - you're using the runtime the bundler presents and emulates on the browser. Native ESM has proven to be quite painful in ecosystems that _don't_ rely on the presence of a bundler to patch over problems, precisely because of the issues of interoping with, I don't know, _literally any existing code_.

I can't think of a concrete benefit to a developer that ESM brings (just pain, but maybe I'm biased by what I'm exposed to). Probably why it's so slow to be adopted.

[WorldMaker]

I've seen some great development environments where all of development/debugging is unbundled ESM directly in the browser. It's going to take a lot of momentum shift to swing the "bundler pendulum" back away from "always" to "as needed" (or even, shockingly, "never"), but I think it is going to happen. HTTP/2+ really does make "never" a bigger possibility than ever before, especially in cases like MPAs (and SSR SPAs that don't mind slower hydration outside certain fast paths).

Also, even some cases with bundlers, some of the modern bundlers (esbuild and swc) are still directly bundling to ESM now as the target. Lazy-loading boundaries and common/shared-code boundaries are just ESM imports and there's no "runtime emulation" there, just native browser loading at that point. They are just taking "small" ESM modules and making bigger ones.

[wwwigham]

I, too, thought http/2+ would encourage unbundled js, but unfortunately in a world where people are used to whole-program minification and dynamic app slicing, I don't think we'll _ever_ move away from bundlers. The build step is here to stay for most serious projects.

ESM may very well be the module system designed for a world that'll actually never exist, and will mostly just be an ill defined compilation target. But hey, maybe the next web module system will do better - those wasm working group people are working hard on their module system - and it's intended as a compilation target from the start, so shortcomings in it can be patched over by tools from the start :)

[WorldMaker]

I do think it is "just" a matter of time/momentum. There's definitely a lot of cargo culting around bundlers ("these bundlers were gifted to us from the gods!", "these were my father's bundlers, I simply must use them!") and there's a lot of developers who "love" scaffolding and boiler plate that are just going to blindly do whatever `create-react-app` or `ng new` or whatever scaffolder of the day briefly masticates then vomits out for their baby bird mouths. Those things (culture, scaffolders) all move slowly (for lots of good reasons, too) and just take time and a few revolutionaries.

HTTP/1 still isn't going anywhere, anytime soon, especially in developer tools (because for better and worse HTTP/2+ requires TLS and developer tools are tougher to build with TLS), so it's still hard to combat the cultural assertions that "bundlers are best practice" and "bundlers are required for performance". But that too is something that shifts slowly over time. There are decades of momentum behind HTTP/1.x.

There's also still so much momentum behind frameworks like React, Angular, plenty more that spent so much time in CommonJS that they still haven't yet sorted out their ESM builds. That's also something getting better with time. Especially now that Node LTS covers enough that you can take an "ESM ONLY (in Node)" approach with confidence.

As I mentioned, I've had the pleasure of working with some projects that were 100% unbundled ESM in development and then spot-bundled (often with esbuild) to highly specific sub-bundles just for Production where Production performance noted improvements. The world of ESM-first is nice when you give it a chance. It will take a bit longer to get to "ESM ONLY, EVERY WHERE", but it still seems to be a matter of time/momentum rather than a problem with ESM.

[tracker1]

I think it's still largely prudent to use bundler tools. I think the biggest issue with not going to ESM syntax comes down to static analysis and tree shaking. It's so much better with proper ESM, and will reduce overhead for the browsers. The bundlers definitely paper over various issues. Being able to import non-js resources like styles, json and other references is useful, to say the least. I don't think this will ever be really practical for direct browser use short of some generational compute and network improvements.

That said, we aren't that far off. Many site are spewing several MB of JS on load, and it's relatively well performing even on modest phones these days. At least relative to 90's dialup where the rule on loads was measured close to 15s. Things are absolutely snappy (mostly). I think the biggest hurdle today is shear entropy. React+MUI+Redux is imo pretty great, and getting to something similar in pure JS would take a lot of effort. Not insurmountable, but significant. There's still a new framework of the month nearly every month in the JS space.

Getting movement is hard. It'll take time and persistence.