The first project is using tsc as the transpiler, which is becoming less common in new build setups. esbuild and babel can already transform TS to JS extremely quickly and with full flexibility, they just don't perform type checking—which could be performed in parallel or even in a completely separate CI pipeline.

Deno devs are saying the type checking iteration cycles are super long, so I think you can't get out of this by just using esbuild.

While I agree with the build times issue and some of the complexity issues, since TS keeps adding new F#-like features I find dubious… isn’t this the classic argument of strongly typed vs loosely typed, just taken down a level?

Using _basic_ typing improves your code maintainability with a trade-off of some build complexity, but it’s still a net win.

Using _extreme_ typing improves some of your code maintainability, but sacrifices developer comprehension and build complexity. It’s not necessarily a TS-specific issue, but TS isn’t helping itself in this regard.

I can understand wanting to move from TypeScript to a non-JS language (is that a thing yet? with WebASM?), but it looks like they were moving back to plain JavaScript.

Surely the cost of slightly longer build times are worth paying for the benefit of having a type system (and as I understand other benefits such as OOP lang features like classes and interfaces, in favor of Javascript's prototyping weirdness)?

I will never understand web developers.

Wow this definitely needs a tag. [2021], 2020 almost even, it’s from January.

What are the reasons for such long builds?

By using plain old javascript (reminds me of pojo!) they are finding wins over typescript.

been using jsdoc typescript in *.d.ts files since a year ago, simply because it's a pain in the ass using tsconfig.

with jsdoc ts it just works out of the box on every vscode installation.