es-module-shims VS single-spa

For full compatibility and extra features, we usually use the library es-module-shims.

You can polyfill for unsupported browsers, it works surprisingly well: https://github.com/guybedford/es-module-shims

https://github.com/guybedford/es-module-shims has a polyfill. (But it is fairly large: 53KB raw, 15KB gzipped, 32KB minified, 11KB minified+gzipped. It’s providing a lot of likely-unnecessary functionality. I’d prefer a stripped-down polyfill that can also be lazily-loaded, controlled by a snippet of at most a few hundred bytes that you can drop into the document, only loading the polyfill in the uncommon case that it’s needed—like how five years ago as part of modernising some of the code of Fastmail’s webmail, I had it fetch and execute core-js before loading the rest iff !Object.values (choosing that as a convenient baseline), so that the cost to new browsers of supporting old browsers was a single trivial branch, and maybe fifty bytes in added payload.)

If we call the shim a framework, would you be ok with it then?

If you want import maps to be supported in any browser, there is an ES Module Shims polyfill which is compatible with any browser that has baseline ES Module Support (i.e. Edge 17+, Firefox 60+, Safari 10.1+, and Chrome 61+).

An example of a polyfill that can be used is the ES Module Shims polyfill that adds support for import maps and other new module features to any browser with baseline support for ES modules (about 94% of browsers). All you need to do is include the es-module-shim script in your HTML file before your import map script:

i often use es-module-shims so i can load npm packages in browsers without a bundler 😎

I explored using client-side service workers for build-less deployment workflows a while back, but the blocker was the initial visit when the service worker hasn't been installed yet. Ended up using es-module-shim's fetch hook (https://github.com/guybedford/es-module-shims#fetch-hook) instead, which worked quite well.

I kept the demo repo around here, in case it's helpful to anyone: https://github.com/lewisl9029/buildless-hot-reload-demo.

The repo itself is quite out of date at this point, but my current project, Reflame, is essentially the spiritual successor: https://reflame.app/

Reflame has the same ideals of achieving the developer experience I've always wanted for building client rendered React apps:

- instant production deployments (usually <200ms)

- instant preview environments that match production in pretty much every imaginable way (including the URL), that can also be flipped into development mode for fast-refresh (for the seamless feedback loop we're used to in local dev) and dev-mode dependencies (for better error messaging, etc)

- close-to-instant browser tests (1-3 seconds) that enable image snapshot comparisons that run with maximum parallelism and only rerun when their dependency graphs change

The problem of course is that browser-support for Import Maps is sadly lacking (only Chrome/Chromium-based at time of writing). There are tricks/shims to get around this, like ES-Module-Shims. I find these approaches to be a little too intrusive, personally.

Single-SPA Framework - One of the most popular choices. It has a large community behind it and offers robust routing and lifecycle management for microapps. Ref - https://single-spa.js.org/

Joel Denning is the visionary behind single-spa, boasting profound insights into the true mechanics of the web and is, in my view, a pioneer in micro frontend architecture. I highly recommend checking the single-spa website and his YouTube channel. While the videos might appear dated at first glance, rest assured, Joel is ahead of his time, and the content remains incredibly relevant today.

You got me curious and I found that single spa is something new to me - if I read https://github.com/single-spa/single-spa then I reckon you can use Svelte(Kit) in such framework - like you can use angular etc

I’ve actually done that “web components as the interoperability layer”!

It was this old angular 1.8 app with new features being written in angular-hybrid-ized angular 8. Ripping out angular-hybrid and separating the angular 1.8 routes from the modern angular routes was difficult, but now they were totally separate.

The only thing linking them together was an object with some RXJS streams in it for state, and a little in-house wrapper “app” who just loaded one component or another depending on the URL and a hash of routes for config. (I’d probably use SingleSPA [1] now. Same thing really.)

We could deploy them separately since the build just ends up being another JS file somewhere that just gets included with a script tag at runtime. No version bumping! No big mega build!

We started replacing the remaining “old” routes 1 by 1 with a “new” counter part. That was the easiest part, and went at a pace devs were comfortable with (fast enough) and business folk could tolerate. (modular enough to not HAVE to be done all at once)

Last I checked, the angular 1.8 stuff is gone years ago. :)

[1] https://single-spa.js.org/

Module Federation is not the unique solution, for example single-spa

You may want to look into using single-spa to run Vue 2 and Vue 3 side by side while you're migrating. Once your app is fully converted, you can stop using single-spa

Single-SPA and module federation are potent tools for building scalable micro-frontends. Single-spa provides a framework for building a modular front-end application. It allows lazy loading of micro-frontends, which helps improve the application's performance. In contrast, module federation enables communication and dependency sharing between different micro-frontends. It reduces code duplication, which can help with scaling an application.

Since micro-frontend allows us to develop applications individually, this also means you can use different frameworks and libraries together to develop each section of this application. Of course, this will have some advantages and disadvantages. If you are using different technologies to serve different parts of the application, it won't be so easy to move developers within teams. However, the door is open, and if you want to do something like that, you could use something like Single SPA, or some other, to help you organize and connect the different technologies into a larger application.