stc VS ECMAScript 6 compatibility table

Wonder no more: https://github.com/dudykr/stc

Written in Rust by the (lead?) dev of SWC

SWC (speedy web compiler) compiles TS to JS

The analogy (by swc's author) would be https://github.com/dudykr/stc

I'm also hoping for STC https://stc.dudy.dev/ but I don't think it will be released any time soon.

MyPy and tsc on the other hand? Please make a Ruff for MyPy and hurry up and fund the author of SWC to develop STC. I'm tired of waiting several seconds after each :w for my quickcheck window to update.

>If we could push JavaScript performance to be another order of magnitude faster

And it would speed up the TypeScript Compiler.

My bet is:

TypeScript typechecker in Rust:

https://github.com/dudykr/stc

typescript(tsc) is the only one that does type checking.

bun, deno, esbuild, swc etc. can parse the syntax, but they chuck the TS (they probably don't even add it to the AST, but I haven't checked).

Keeping up with syntax is very doable. It doesn't change often, and updating the parser when it does isn't much work.

There are some past/ongoing projects[1][2] to create type checkers faster than tsc, but they aren't going to reach full parity and probably don't plan on keeping up with language features.

[1] https://github.com/dudykr/stc

Well the checker is in progress.

http://kangax.github.io/compat-table/es6/

This page lists features from es6 (and newer versions linked at the top) along with compliance to the spec. First column is the current browser, second is babel+corejs polyfills.

Overall, babel gets about 70% of the way there.

Case in point: Tail Call Optimization has been part of the JS spec since ES6, but remains completely unimplemented in all mainstream browsers/engines besides Safari[1]. For all but the most predictable inputs, you're pretty much forced to use loops where recursion would otherwise be preferable.

Additional case in point: async Iterables cannot be processed as a piped stream. You must use the for await construct, which is a shame considering the FP niceties that the Array type already provides for more traditional lists. Once again, you are forced to use an imperative construct unless you specifically want to defeat the purpose of using an Iterable in the first place by trying to convert it into an Array (... and potentially choking in the process, I might add!).

[1]: https://kangax.github.io/compat-table/es6/

Eventually the browsers started racing to near-full ES6 compatibility. I remember following ES6 progress in realtime with articles and with compatibility tables http://kangax.github.io/compat-table/es6/ . But many people are acting like that either didn't happen, or like it was a one and done thing (despite the ESNext naming shift to avoid the focus on numbers). So we see people just hand-waving away the importance of polyfills like in this gem:

> https://kangax.github.io/compat-table/es6/

Oh man this was a rough one both for FF and Chrome but Chrome did perform better slightly on cursory glance.

Thanks for providing these links, they're definitely a good rule of thumb benchmarks to test new browsers

Javascript / CSS language syntax: can see availability for Javascript here - https://kangax.github.io/compat-table/es6/

I say this as a JS user, but there is no singular JavaScript (realistically, it's not even JavaScript but instead ECMAScript). There is no one place to go that lays out all of what the language can or can't do the way PHP and Python do. The ECMAScript board makes recommendations, then the browsers and runtimes implement features of the recommendations. This site does a good job laying out which features are implemented for browsers and runtimes based on the flavor of the ECMAScript standard. This unique experience can be especially frustrating for someone learning JavaScript and coming from another language that does not have this problem.

https://kangax.github.io/compat-table/es6/ has a column for "current browser"