FrancescElies commented 1 year ago

Suggestion

In pyright there is reportUnusedCallResult but I couldn't find anything similar in TypeScript: TSConfig Reference, please correct me if I missed it.

🔍 Search Terms

reportUnusedCallResult
call result
unused call
unused

✅ Viability Checklist

My suggestion meets these guidelines:

[x] This wouldn't be a breaking change in existing TypeScript/JavaScript code
[x] This wouldn't change the runtime behavior of existing JavaScript code
[x] This could be implemented without emitting different JS based on the types of the expressions
[x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
[x] This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

A similar option to pyright's reportUnusedCallResult could be added and being disabled it's default state and maybe enabled with strict flag?

📃 Motivating Example

// some code

get_chichi()

// more code

One reads this and wonders, why would one _getchichi here, chichi is not used anywhere.

Maybe the person who wrote this forgot to use the value?
Maybe is a leftover and can be removed?
Maybe this function has a side effects and it should be renamed to reflect that?

💻 Use Cases

Reminding the developer about unused call results makes it harder to see code like in the example above.

One problem I see with the proposal above is that there seems to be no convention in javascript for throwaway variables, but according to What is the equivalent of python's _ in javascript? - Stack Overflow and naming - What's the idiomatic name for a throwaway variable? - Software Engineering Stack Exchange dummy, temp, trash, black_hole, garbage seem to be widely used.

After tsc complains about the code above one would be forced to either remove that call, assign the result and use it or assign it to a throwaway variable.

MartinJohns commented 1 year ago

This sounds better suited as a linter rule instead of being part of the compiler. But I'd expect the false positives to be immensely.