[MaxArt2501]

For me, the main problem is that TS doesn't follow semantic versioning and this leads to a fragmentation of libraries support - unless they also provide multiple type definitions (some of them actually do) - and migrating to newer versions is usually harder, because breaking changes happen so often. So I guess point i) is correct.

Let's see the others.

ii) It's true that many libraries don't have type definitions, but the most used ones have an externally-maintained corresponding @types/### package that solves the problem. And even if they don't, how is it the fault of TS? The alternative is no type documentation at all - is that better for you?

iii) Yes, error messages are something that can be improved, but then again, the alternative is no static error and eventually an even more laconic runtime error. Would that be better? At least, TS catches that there's a problem before you run the code.

iv) Compilation adds a burden to the CPU, not the developer. But anyway, it's a one-time process, and unless it takes 30 minutes it shouldn't be a problem. There are new, much faster compilers nowadays, like esbuild and SWC, plus other tooling tricks like module caching, that makes your local development almost feel like there's no compilation at all.

I won't discuss the merits of the adoption of TypeScript. Since I started using it - except for very simple projects - I always felt like I'd be way less productive without it. And I actually had the confirm recently, when I had to work on a Loopback@3 BE that somehow is in JavaScript (even though Loopback 3 does support TS).

It's been a mess. Trying to understand the models, the signature and the sense of all the entities has been a nightmare. The documentation for LB v3 is badly maintained and sometimes broken, and this adds even more difficulty. Some dev tried to add some JSDoc info here and there, but it's not nearly sufficient to understand what's going on without investing hours of study of the existing code.

This is part of the cause that prevented the team to upgrade to LB@4, so much that I even suggested to redo the BE altogether in Nest (save for the core business logic parts), rather than trying to make a sense of it.

So yeah, I'll stick to TS for the foreseeable future, and strongly suggest all the teams I'm going to work with to do the same.