2y ago

Me, migrating my code from JavaScript to TypeScript:

32 comments

Might as well not use TypeScript
- Just as irritating as seeing people use linters only to have a lot of files with @ts-ignore all over the place... Like why even bother?
  
  oh you've got a private variable that I want to use? No worries, (foo as any)['secret'].
- using any is actually much worse than using TS, because you're basically telling the compiler "don't help me here".. at least with JS the IDE is gonna help you.. :/
- That's the joke
- I don't follow, stamping every function with : any lets you merge the branch and deploy it... trying to properly type everything extends the initial migration time likely to a level where management just says no.
  
  Use a combination of allowJs and ts-ignore, do progressive enhancement, and convert your codebase file by file. Adding any everywhere literally turns off type checking altogether codebase wide, including type inference. It also means a huge PR that's both just noise that needs to be fixed later, and messes with your git history (good luck getting anything useful out of blame or bisect now).
  Just getting a green build doesn't mean things are okay. You're worse off than before doing that.
- tbh I don't remember why I'm using TypeScript
  
  Cause otherwise it's plain JS :/
- Forreal. Even a bespoke inferred return type is better than any 9 times out of 10.
  
  This is the only reason I haven't pushed my team to switch. I'm worried too many of them will be OP.

It's a good way to get started, and then incrementally type as much as you can, preferably everything.
Later on, or if you start a new project with TypeScript, it's a good idea to turn on noImplicitAny and only allow explicit any in very specific framework level code, unit tests or if you interface with an untyped framework.
The hassle really pays off later.
- this is terrible advise - you should be using unknown. using any you're basically disabling TS and will be under the false assumption that your code is ok while it's most likely missing a lot of runtime checks
- But if your code ever integrates with javascript you still need any everywhere so it's pretty pointless
  
  Not true, in the absolute worst case, unknown is what you should be reaching for, but it's pretty rare that you can't create some kind of type to interface with JS if it's not already got types. You can even use jsdoc comments as type hints in the JS too if you own that code.
  My not particularly hot hot-take: There's basically no legitimate use case for any apart from "I don't have time to type all this now, because I'm converting a massive project from JS to TS"
  
  Not necessarily, depending on your situation you can type the JS code yourself.
  If the team making the JS code were using jsdoc then the Typescript compiler can recognize the comments and use it for type checking.
  In some instances the compiler can infer types from JS code to do some basic validation.
  Even if the external JS code is recognized as any, your own code that's using it still has types, so it's better than nothing.

an any
- But it’s “a colon any” 🧐

I knew my any key would be useful one day.

Why not use assembly ?

Typing < type hinting

Nah this isn't the way, friend. Instead of adding a bunch of useless anys all over the place, start typing in one part of the application and exclude the rest using a path pattern. Or simply allow .js and only change the extension for files you've typed. Doing this is just wasting time and creating false assurances of type safety.
It's not that hard to define correct, meaningful types. Often vscode already has implicitly determined them for you; just mouseover the variable.

I wish I did that, at this point my TypeScript template errors are as long as C++'s ._.

32 comments