sucrase

I've tried this before, with a service worker[1] that intercepts TS/X-ish requests, and directing them over to sucrase[2] to compile to JS, before being loaded by the browser. Unfortunately sucrase seems to be no longer maintained. [1]: https://github.com/altbdoor/sucrase-build-iife [2]: https://github.com/alangpierce/sucrase

One slightly annoying thing about esbuild/swc is that they're faster by literally not being equivalent to Babel. esbuild intentionally does not emit ASTs, and SWC has their own flavor that is not compatible with Babel. Furthermore, both are written in non-JS languages, meaning any sort of plugin system either has to be written in Go/Rust respectively, or suffer massive performance hits from crossing the JS runtime boundary. SWC abandoned plugins in JS for this reason. The dirty secret is, as Sucrase (https://github.com/alangpierce/sucrase) reveals, just that Babel is slow and the codebase really pays homage to the project name. Simply computing the config for transforms takes dozens of milliseconds on my machine as it does a bunch of filesystem reads. So esbuild/swc etc. aren't gaining some magical compiled language speedup, they're just.

You can run multiple processes of Sucrase if you want at which point it will still be faster than threaded SWC/esbuild. This is currently up to the user, but hopefully, the authors follow through on this issue and integrate an easier way for users to do this (though I don't know if they want that as core functionality). https://github.com/alangpierce/sucrase/issues/730 JS JIT creators don't get enough credit for their string implementations. Not much comes close when you consider both performance and robustness they packed into the C++ implementations that JS is actually using.

Sucrase is faster than SWC and esbuild in single-threaded performance and something like 20x faster than babel. https://github.com/alangpierce/sucrase The real issue isn't JS, but is the lack of profiling (as shown here) combined with wanting to be everything to everyone leading to layers of bloated abstraction.

Hi, Sucrase author here. To be clear, the benchmark in the README does not allow JIT warm-up. The Sucrase numbers would be better if it did. From testing just now (add `warmUp: true` to `benchmarkJest`), Sucrase is a little over 3x faster than swc if you allow warm-up, but it seemed unfair to disregard warm-up for the comparison in the README. It's certainly fair to debate whether 360k lines of code is a realistic codebase size for the benchmark; the higher-scale the test case, the better Sucrase looks. > worse it disables esbuild and swc's multi-threading At some point I'm hoping to update the README benchmark to run all tools in parallel, which should be more convincing despite the added variability: https://github.com/alangpierce/sucrase/issues/730 . In an ideal environment, the results are pretty much the same as a per-core benchmark,

Yes, you technically can write high-perf JavaScript code... https://github.com/alangpierce/sucrase/blob/153fa5bf7603b9a5... But freaking SIGH I don't want to. I prefer coding in environments that don't require unrolling loops by hand.

but the benchmark is stupid: https://github.com/alangpierce/sucrase/blob/main/benchmark/b... > Like all JavaScript code run in V8, Sucrase runs more slowly at first, then gets faster as the just-in-time compiler applies more optimizations. From a rough measurement, Sucrase is about 2x faster after running for 3 seconds than after running for 1 second. swc (written in Rust) and esbuild (written in Go) don't have this effect because they're pre-compiled, so comparing them with Sucrase gets significantly different results depending on how large of a codebase is being tested and whether each compiler is allowed a "warm up" period before the benchmark is run. (worse it disables esbuild and swc's multi-threading... https://github.com/alangpierce/sucrase/blob/main/benchmark/b... https://github.com/alangpierce/sucrase/blob/main/benchmark/b...) fa

Sucrase is written in JS and boasts the highest line throughput of any competing transpiler https://github.com/alangpierce/sucrase Time Speed Sucrase 0.57 seconds 636975 lines per second swc 1.19 seconds 304526 lines per second esbuild 1.45 seconds 248692 lines per second TypeScript 8.98 seconds 40240 lines per second Babel 9.18 seconds 39366 lines per second

Sucrase is faster or really close to SWC (see rhe benchmarks https://github.com/alangpierce/sucrase). Everyone still uses Babel because of the transforms. And yes, Babel can also be made faster if enough effort is dedicated into it. it's not an impossible feat.

Webpack does way more than esbuild, including running a typechecking compiler instead of just transpiling, running compilers able to downlevel emit to ES5 and providing a deep plugin architecture allowing you to hook into any bit you like. But yes, it hasn't been designed with speed in mind - it has been designed for maximum extensibility instead. Its the same reason why Babel is slow compared to sucrase (written in JS, currently faster than SWC and esbuild but doing somewhat less - https://github.com/alangpierce/sucrase) tsc has in fact been designed with speed in mind (I've been following the project since before it moved to GitHub, which is when they redesigned it for speed). Going beyond 1 order of magnitude performance improvement while implementing the full feature set is highly unlikely.

That's basically what Sucrase.js is: https://github.com/alangpierce/sucrase

Sucrase is what you're looking for. When converting to ES6+, it's actually almost 2x as fast as esbuild on a single thread (though slower in aggregate). As they point out, there's a JIT warmup time. Testing against small projects that don't allow this makes JS transpilers look much worse than they actually are in real-world projects. https://github.com/alangpierce/sucrase https://github.com/alangpierce/sucrase/blob/main/benchmark/b...

There is also swc which is fast because... its written in Rust https://swc.rs/ But there is also sucrase which is fast because.. its written in TypeScript? https://github.com/alangpierce/sucrase