[Proposal] Stop transpiling some builds to ES5 #1435
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peaBerberian
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Apr 30, 2024
| depending on your project). | ||
| If you need to provide support for the `MULTI_THREAD` feature on those platforms, we | ||
| recommend that you use a transpiler tool on that worker file to make it compatible to ES5. | ||
| Examples of transpiler tools are [babel](https://babeljs.io/) and [swc](https://swc.rs/). |
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Pro-tip: we can just throw the hot potato to the application :D
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This was referenced May 6, 2024
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For purposes where we need to generate a bundle (the demo, the worker files, the RxPlayer bundle builds), we're progressively removing our reliance on webpack toward esbuild. It began with the demo page originally for performance reasons, but we found out that the esbuild behavior and API was much simpler to understand than webpack's, and so we ended up also prefering to rely on it for our worker build. Considering that we since the v4 only rely on TypeScript with no bundling step for our "regular" build (and our home-made scripts in the `./scripts` directory), we thus ended up having no reliance on webpack for most of our builds. However at #1400, we noticed that we might also need to provide an ES5 version of our worker file (at least for the PlayStation 4), and I found that having ES5 support through esbuild is not straightforward (evanw/esbuild#297). Historically, [babeljs](https://babeljs.io/) was used to translate to ES5 - and that's the one I know, so I tried using it on the bundle made by esbuild. However it turns out that there's no resource for how to use babel like this - not integrated as a bundler's plugin (here we just wanted to translate an ES2017 already-made bundle to es5) so I just gave up and relied on webpack for specifically that ES5 build. However this both added some perceptible delay in our build, and we now relied on two different bundlers in our `npm run build` main build script, which made me un-comfortable in terms of maintainance and understanding of how our build step worked. So I re-looked around and read about [`swc`](https://swc.rs/), which seems to be some kind of babel competitor with some credibility (though they advertises themselves as a """platform""", I would have preferred a clearer term but ok), with some differences, including speed, but what is most interesting here is that it can just be run as a standalone transpiler (what I mean: not embedded in a bundler). By using it, I've been able to remove reliance on webpack (and babel) in our regular build steps (produced by `npm run build`) which should be realistically used by 99.9999% of applications (approximately!). The only exception where both webpack and babel are still used is to produce our bundles attached to each release notes (they expose the RxPlayer through `window`, like our grandfathers did) - which I guess are rarely relied upon. Still, we should probably remove reliance on webpack there in the future. Swc is maintained apparently by volunteers, and is less known than babeljs, so there's still that. Also, the bundler and transpiler JavaScript landscape is __VERY__ active (even in JavaScript terms) right now with projects like [rolldown](https://rolldown.rs/) and [oxc](https://oxc-project.github.io/) so sadly it may be not the last update of this part of our build process.
As a follow-up effort to #1420 (on which this work is based on), I attempt here to stop relying on webpack for the generation of our "legacy bundles", which are rarely used RxPlayer bundles that are communicated through release notes and which exposes the `RxPlayer` class through the global scope (`window`). The idea, the same than for #1420, was to simplify our bundling process by relying only on esbuild for this (instead of both webpack and esbuild depending on the situation). I chose esbuild over webpack here mainly because I better understand its role, behavior and most-of-all its API than webpack's - though its (much) faster bundling speed is a also a very good argument for this. Like for #1420, the last remaining issue was our usage of the babeljs transpiler to transpile to ES5 (our legacy bundles are ES5), but that's been fixed by switching to swc for that part. Our legacy bundle was purely configured by the `webpack.config.js` file at the root of our project that I here removed. To replace it, I re-purposed our `scripts/bundle_worker.mjs` script into a more generic `scripts/run_bundler.mjs` script for which we're now supposed to indicate the wanted input and output files. -- Still, I encountered an important issue while doing that in that I did not understand how we're supposed to indicate to esbuild that our entry file's export has to be exported through the global scope (all my introduction about the esbuild API being simpler to understand now loses all credibility!). I tried playing with its [`globalName`](https://esbuild.github.io/api/#global-name) and [`format`](https://esbuild.github.io/api/#format) configuration options which seem linked to that but couldn't make it work. For now, I gave up, adding a `__GLOBAL_SCOPE__` compile-time constant (boolean) to `src/index.ts` which has to be set to `true` before bundling if you want to export the RxPlayer through the global scope.
This is built on top of #1425 itself built on top of #1420, which removes most dependencies to webpack (besides tests, that we'll need to also change anyway considering the fact that `karma-webpack` has an old reported issue on macOS with our build). We planned to release in our future 4.1.0 an ES5 version of our worker file and as a lesser feature an ES5 "legacy" build (the one linked to release notes - not the one published on npm). Providing an ES5 version of our worker file was especially added to support the `MULTI_THREAD` feature on PlayStation 4 devices. However I sadly propose here that we roll back that attempt of support (just of the `MULTI_THREAD` feature, the PlayStation 4 stay officially supported and tested). --- After multiple attempts (myself and then @Florent-Bouisset), we realized the complexities and costs of maintaining a supplementary ES5 version of builds. We initially tried to switch from a webpack+babel mix to swc on a bundle already produced by esbuild. The global idea was to simplify our bundling process by designing an architecturally simple and low-maintainance process made of a separate bundling step then transpiling step on the bundling result. But we realized that this philosophy doesn't seem to be compatible to those tools. When combined with the fact that their documentation is often either lacking or too complex, than some of our questionning to maintainers led to poor answers and that the JS tooling ecosystem appears to be still changing very fast, I'm not sure that I want to guarantee support of ES5 for our hopefully long-lived v4 right now.
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This is built on top of #1425 itself built on top of #1420, which
removes most dependencies to webpack (besides tests, that we'll need to
also change anyway considering the fact that
karma-webpackhas an oldreported issue on macOS with our build).
We planned to release in our future 4.1.0 an ES5 version of our worker
file and as a lesser feature an ES5 "legacy" build (the one linked to release
notes - not the one published on npm).
Providing an ES5 version of our worker file was especially added to
support the
MULTI_THREADfeature on PlayStation 4 devices.However I sadly propose here that we roll back that attempt of support
(just of the
MULTI_THREADfeature, the PlayStation 4 stay officiallysupported and tested).
After multiple attempts (myself and then @Florent-Bouisset), we realized
the complexities and costs of maintaining a supplementary ES5 version of
builds.
We initially tried to switch from a webpack+babel mix to swc on a bundle
already produced by esbuild.
The global idea was to simplify our bundling process by designing an
architecturally simple and low-maintainance process made of a separate
bundling step then transpiling step on the bundling result.
But we realized that this philosophy doesn't seem to be compatible to
those tools. When combined with the fact that their documentation is
often either lacking or too complex, than some of our questionning to
maintainers led to poor answers and that the JS tooling ecosystem appears
to be still changing very fast, I'm not sure that I want to guarantee
support of ES5 for our hopefully long-lived v4 right now.