Not saying I agree, but this is a completely valid viewpoint.

When I initially saw Typescript, I thought the point was to add features from strongly-typed languages and then transpile into Javascript. (IE, a more modern version of GWT, a Java to Javascript transpiler.)

The point of the article, though, is that Typescript works best when its extensions to the language can simply be dropped. That's clearly a "we've worked with this for many years and this is a big lesson from experience" statement, so I wouldn't discount it.

Typescript works fine with it's extensions to the language. In fact, I can't imagine how it would not work fine - that would be a serious issue in the official compiler or tools.

It's the other tools that author is/was using that are having issues. It's silly to provide blanket statements about very useful features like enums or namespaces just because some third-party tool is struggling with them IMO.

I recently picked up TypeScript and I sort of agree with the author. It’s just so much cleaner to use Types instead of enums. That being said, I don’t think enums are bad if there is a good reason to use them. Checking if something is a type of X isn’t one such thing in my opinion, but that’s probably religion.

Namespaces mKe no sense to me. It’s probably because Microsoft drives TypeScript, but even though I was a C# developer for 10 years before moving on, they’ve just always been terrible to me. Their functionality is the sort of thing that is nice in theory, but really terrible in real world projects that run for years with variously skilled developers in a hurry.

Private is silly to me, but this is mostly because classes are silly to me. I can see why you’d want it if you use a lot of classes, I just don’t see why you would do that unless you’re trying to code C# in TypeScript. One of the things I loved the most about switching from C# to Python was how easy it was to use dictionaries and how powerful they were. The combination of TypeScript interfaces, Types and maps is the same brilliance with type safety. But once again, it’s sort of the thing where classes sometimes make sense, and when they do, so might private.