[wyriwyg]

IMHO type checking for dynamically typed languages should be done by the IDE instead of messing up the language itself. Fortunately at some point there will be an addon for your favorite IDE that does the type checking without touching your code. Microsoft could have developed such a rigorous type check addon for VSCode, but (unfortunately) instead they went for Typescript, no clue why they preferred to do the latter, maybe another throw to dominate the no1 browser language?

[qbane]

JavaScript is inherently untyped. Either the programmer tries to be very careful to make it type safe, or someone invents a programming language that can only compile to a sound subset of it. TS heads for the latter way. But things quickly go out of control when you introduce dependencies, and even a dependency without interface file can pollute your codebase with "any". I do not think TS would be mainstream if there were not many packages on npm that had included a type definition. On the other hand, a type checker/inferencer that "does less things" like Jedi has proved great success in Python community.

[pjc50]

I don't understand this point of view: types are part of the code? Perhaps one could eliminate 90% of the need to write them down with aggressive use of Hindley-Milner, but in many places they're a deliberate choice.

[randomdata]

The discussion taking place is about type checking plain Javascript. The comment you replied to questions why Microsoft didn't go down that road, something they ended up doing eventually anyway, instead of introducing a new language.