es-module-shims VS reagent

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The repo itself is quite out of date at this point, but my current project, Reflame, is essentially the spiritual successor: https://reflame.app/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

Generating `HTML` from lisps has poisoned any other approach for me, see for example https://www.neilvandyke.org/racket/html-writing/, https://reagent-project.github.io/, and https://edicl.github.io/cl-who/

Hiccup syntax for Clojure uses hash maps (curly braces) for attrs, e.g. `{:style {:background "red" :margin "1em"}`

See Reagent which uses Hiccup synta: https://reagent-project.github.io/

    (defn simple-component []

* Single-Page App: shadow-cljs for the build concerns (https://github.com/thheller/shadow-cljs), Reagent with Re-frame for complex/large app (https://reagent-project.github.io and https://github.com/day8/re-frame). Even if we now prefer using HTMX (https://htmx.org) and server-side rendering (Hiccup way of manipulating HTML is just amazing, https://github.com/weavejester/hiccup).

The API documentation lists the most commonly and rarely used parts before going into detail and there are many usage examples.

Reagent has a nice intro tutorial (classic todo-app): http://reagent-project.github.io and many other helpful tutorials and resources for beginners: https://cljdoc.org/d/reagent/reagent/1.2.0/doc/documentation...

However, since Reagent is still stuck with class-components for more complex behavior and relies on Hiccup, which is nice but has a performance cost compared to pure React, I am unsure about its future. Like some others in the Clojure community, I have moved to thin React wrappers like Helix and use Refx to integrate those with re-frame. It may be a bit confusing right now for beginners since there is no “golden path”.

Also, unfortunately, many smaller libraries are poorly documented and it seems like it is expected from the developer to dig into the source code to find out what’s going on.

What I found the most difficult as a beginner was how to setup a project in ClojureScript in the first place, like all the configuration in shadow-cljs, how it interacts with deps.edn, how it integrates with npm, the REPL, etc. But dev/build config has always been a weak spot for me, so it might be just that.

Overall, I still very much enjoy working with Clojure(Script), more than in any other language. Anyone who likes Lisps and functional programming should give it a try (and be sure to watch Rich Hickeys amazing talks!).

have you tried cljs and reagent? it’s a different vibe.

my bootstrap: https://github.com/nathants/aws-gocljs

the project: https://reagent-project.github.io/

Clojure people have been doing this for a decade or so. It’s really so much better to work with. All started with Hiccup and when React came along you got Reagent and many more developments building on the idea.

> But Reagent supports functional components as well, with hooks and all.

I addressed this already: while reagent is able to emit function components, there is a performance penalty to this.[1]

> I also very much like Hiccup, and so do many of us, because code is data and data is code, and Helix has decided not to support that.

Hiccup is convenient to write, but it is a constant run-time cost and a significant storage cost given that you have to store long series of constructors to cljs.core.PersistentVector in your bundle, have the JS runtime actually construct the vector, then pass it through a Hiccup interpreter to finally produce DOM nodes and throw away the persistent vector, only to repeat this entire process again on re-render.[2]

> Helix has decided not to support that.

That is simply not true. From the Helix documentation[2],

> If you want to use libraries like sablono, hicada or even hx hiccup parser, you can easily add that by creating a custom macro.

These are all Hiccup interpreters you can readily use.

IME there is very little difference between using the $ macro in Helix and writing Hiccup. I do not really miss Hiccup when I use Helix, and you still have data as code ;)

While this is from an unrelated project, there are benchmarks[3] done against Reagent that demonstrate the sheer overhead it has. In practice it is not a big problem if you rarely trigger a re-render, but otherwise it is a non-trivial cost, and if you want to use modern React features (like Suspense), there is a lot of r/as-element mingling going on, converting cases, etc. that simply make Reagent feel more tedious to use than Helix.

Also, the newer UIx2, which largely borrows from Helix, is "3.2x faster than Reagent" according to one of the contributors.[4]

I think it'd be worthwhile to benchmark all of these libraries against each other and record the data in one place. Maybe I'll get around to doing it this weekend :)

---

[1] https://github.com/reagent-project/reagent/blob/master/doc/R...

[2] https://github.com/lilactown/helix/blob/master/docs/faq.md#w...

[3] https://github.com/roman01la/uix#benchmarks

[4] https://github.com/pitch-io/uix/pull/12

Reagent is peak React. All the good stuff without any of the hook and readability problems the article describes.

No affiliation, happy user for years.

https://github.com/reagent-project/reagent