Parameter hints while overriding methods

[JacksonKearl]

Suggestion

It would be nice to get parameter hints while overriding methods or implementing abstract methods.

🔍 Search Terms

• parameter hints
• overriding methods
• abstract parameters

✅ Viability Checklist

My suggestion meets these guidelines:

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

⭐ Suggestion

When implementing an abstract class or overriding an existing class's methods, it would be great to be able to see the parameter hints for that method in the editor.

📃 Motivating Example

abstract class A {
  abstract foo(param1: string, param2: number, param3: boolean): void;
}

class B extends A {
  foo(/*trigger parameter hints here, see nothing*/)
}

type AA = {
  foo(param1: string, param2: number, param3: boolean): void;
}

const BB: AA = {
  foo(/*trigger parameter hints here, see lovely results*/)
}

Playground. (use Ctrl/Cmd+Shift+Space to trigger parameter hints)

💻 Use Cases

I'd use this when implementing abstract classes to remember the parameters I get to use.

[DanielRosenwasser]

Technically what you're seeing with the signature help on that method declaration is a bug, and I only haven't filed it because it's so helpful. 😅

The problem is that it's a bit misleading in the case of derived methods without #23911