How an Anti-TypeScript “JavaScript developer” like me became a TypeScript fan

Post by pattrn » Tue, Mar 02, 2021, 7:44 PM UTC

lhorie wrote: post #122

madeofpalk wrote: post #2

It's probably worth taking a step back and interrogating why the actual "Why was I Anti-TypeScript?" a little bit more and use it as an opportunity for broader self development. The author didn't use and understand something, and rather than trying to they instead just defaulted to rejection. It's midly disapointing seeing this in people who label themselves as "Senior".

Ironically, as someone who has experience w/ both fast-and-loose JS and with "properly" statically typed languages, my beef with typescript is precisely that it allows people to be fast and loose, sometimes in ways that are not super obvious. For example: type Thing = { name: string, }; function getThing(): Thing { return JSON.parse('{"error": "invalid id"}') } const thing: Thing = getThing(); // lie to me! console.l…

Post by throwaway4good » Tue, Mar 02, 2021, 7:58 PM UTC

   type State = { id: "initial" } | { id: "running", speed: number }

   const f = (s: State) => {
     switch (s.id) {
       case "initial": // s.id available
         break;
       case "running": // s.id and s.speed available
         break;
     }
   }

Post by WorldMaker » Tue, Mar 02, 2021, 8:01 PM UTC

lhorie wrote: post #147

madeofpalk wrote: post #129

Earlier quoted context omitted.

The "curse" of Typescript is that it's built on Javascript, so you can tell it to lie to you all the time. This is the problem with introducing Typescript to a larger group of Javascript developers who arent all on board (because of either experience or being stubborn) - you still need to establish good habits and patterns for how to write typescript. I'm working through the very lie you're showing now because the di…

> you still need to have good developers writing good code, but TS will make it easier Very true. Typescript is still immensely helpful in the sense that it will complain if you pass a Thing to a function expecting a Foo, regardless of the fact that Thing is meant to be a thing but is actually an error. But IMHO, by sticking to a decision to be lean in terms of transpiled JS, TS suffers greatly from cases like the on…

    function isThing(value: unknown): value is Thing {
      return typeof value === 'object' && typeof value.name === 'string'
    }

Post by dep_b » Tue, Mar 02, 2021, 8:03 PM UTC

matsemann wrote: post #34

While I'm fan of statically typing, there is something with Typescript I don't like, but don't know exactly what it is. In my day-to-day it's mostly Kotlin and Elm, which also are both statically typed, which I don't mind and mostly don't even notice. But with Typescript it is as if I'm always fighting the compilator, trying to make it happy with whatever code I wrote. Maybe it's just the JS ecosystem being too lax t…

Post by toolslive » Tue, Mar 02, 2021, 8:05 PM UTC

  >   const x = 'xxxx'
  >   if(x === undefined) {
  >       console.log('never happens')
  >   }