typescript - Eslint returns with no-unused-vars

Question

I have setup eslint to warn me on unsed vars

rules: {
  '@typescript-eslint/no-unused-vars': ['error', { args: 'none' }],
}

Now I have a typescript class which look like this:

import { User } from './user';

export class MyClass {
  async myMethod(): Promise<User> {
    // Some code
  }
}

When I run eslint I get this error

error  'User' is defined but never used  @typescript-eslint/no-unused-vars

Why is eslint warning me? In my eyes the variable is used.

question from:https://stackoverflow.com/questions/65938767/eslint-returns-with-no-unused-vars

Answer 1

In your example, we see only the type Promise, which doesn't mean that you are using User in your Method, but only to define a type. Eslint is expected :

import { IUser} from './user'; // interface for User object
import { User } from './user'; // User object

export class MyClass {
  async myMethod(User: string): Promise<IUser> {
    // Some code with User parameter
  }
}

Your Eslint rule will apply only on User object, and not on the interface.

some readings: https://basarat.gitbook.io/typescript/future-javascript/promise