4 ms·

TypeScript is not a good foundation to be building on. The language has very complex semantics and the only "spec" is the main implementation, which is also evo

TypeScript is not a good foundation to be building on. The language has very complex semantics and the only "spec" is the main implementation, which is also evolving.

mort96 2y ago
Yet it's the best we have at the moment in terms of statically typed JS (other than JSDoc which encodes the type system in comments, which .. has its own issues).
- crabmusket 2y ago
  Does JSDoc even have a type checking system? The point of TS is that is actually does something with your declared types. JSDoc is nice... for docs being interpreted by a human. But unless those are used to create red squigglies then it's kind of arbitrary. I've used JSDoc with TS's type syntax and typechecker in JS files. Which is fine - I find it subjectively uglier but I know some prefer it. But it's still TS that's doing the actual work of determining if all my annotations are compatible when the rubber hits the road.
  - mbarneyme 2y ago
    JSDoc provides the exact same level of type safety as TypeScript, because the TypeScript Language Server/CLI themselves are what does the type checking. Using JSDoc removes the need to transpile your code before executing it. You still want to type-check your code (with a `tsc --noEmit` or similar) in CI, just like you'd run unit tests/a linter/etc.
    - crabmusket 2y ago
      Yes, that's my point. JSDoc isn't an alternative to TypeScript if you want your types to actually be checked.
postepowanieadm 2y ago
And has some really odd behaviors like https://github.com/microsoft/TypeScript/issues/17053 https://github.com/microsoft/TypeScript/issues/17053
- c-hendricks 2y ago
  Are you saying typescript should parse regular expressions? Turn on `noUncheckedIndexAccess` and it works as you expect (plus forces you to check all the places you're doing unchecked access). https://www.typescriptlang.org/play/?noUncheckedIndexedAccess=true#code/MYewdgzgLgBAtgQysAFjAvDARArA6RZFACgHpiEBKAfmICMbTKBuAKAEsAzGYw1GAITpMYAK4AbcZRgBvVjAUxQkWAG0ANDASa6AXQzwkqNoq3iApgCcoFPFBABVAA5OrAYQQRzxSi3mKEC2t6O0cXd09vXzYAXyA https://www.typescriptlang.org/play/?noUncheckedIndexedAcces...
  - swift 2y ago
    Regular expressions are part of the language, so it's not so unreasonable that TypeScript should parse them and take their semantics into account. Indeed, TypeScript 5.5 will include new support for syntax checking of regular expressions[1], and presumably they'll eventually be able to solve the problem the GP highlighted on top of those foundations. [1]: https://github.com/microsoft/TypeScript/pull/55600 https://github.com/microsoft/TypeScript/pull/55600
    - c-hendricks 2y ago
      That's crazy, in the best way

TypeScript is not a good foundation to be building on. The language has very complex semantics and the only "spec" is the main implementation, which is also evolving.

mort96 2y ago

Yet it's the best we have at the moment in terms of statically typed JS (other than JSDoc which encodes the type system in comments, which .. has its own issues).

crabmusket 2y ago
Does JSDoc even have a type checking system? The point of TS is that is actually does something with your declared types. JSDoc is nice... for docs being interpreted by a human. But unless those are used to create red squigglies then it's kind of arbitrary. I've used JSDoc with TS's type syntax and typechecker in JS files. Which is fine - I find it subjectively uglier but I know some prefer it. But it's still TS that's doing the actual work of determining if all my annotations are compatible when the rubber hits the road.
- mbarneyme 2y ago
  JSDoc provides the exact same level of type safety as TypeScript, because the TypeScript Language Server/CLI themselves are what does the type checking. Using JSDoc removes the need to transpile your code before executing it. You still want to type-check your code (with a `tsc --noEmit` or similar) in CI, just like you'd run unit tests/a linter/etc.
  - crabmusket 2y ago
    Yes, that's my point. JSDoc isn't an alternative to TypeScript if you want your types to actually be checked.

postepowanieadm 2y ago

And has some really odd behaviors like https://github.com/microsoft/TypeScript/issues/17053 https://github.com/microsoft/TypeScript/issues/17053

c-hendricks 2y ago
Are you saying typescript should parse regular expressions? Turn on `noUncheckedIndexAccess` and it works as you expect (plus forces you to check all the places you're doing unchecked access). https://www.typescriptlang.org/play/?noUncheckedIndexedAccess=true#code/MYewdgzgLgBAtgQysAFjAvDARArA6RZFACgHpiEBKAfmICMbTKBuAKAEsAzGYw1GAITpMYAK4AbcZRgBvVjAUxQkWAG0ANDASa6AXQzwkqNoq3iApgCcoFPFBABVAA5OrAYQQRzxSi3mKEC2t6O0cXd09vXzYAXyA https://www.typescriptlang.org/play/?noUncheckedIndexedAcces...
- swift 2y ago
  Regular expressions are part of the language, so it's not so unreasonable that TypeScript should parse them and take their semantics into account. Indeed, TypeScript 5.5 will include new support for syntax checking of regular expressions[1], and presumably they'll eventually be able to solve the problem the GP highlighted on top of those foundations. [1]: https://github.com/microsoft/TypeScript/pull/55600 https://github.com/microsoft/TypeScript/pull/55600
  - c-hendricks 2y ago
    That's crazy, in the best way