Eslint is back and it's cracking down on unused variables with no

Question

Eslint is back and it's cracking down on unused variables with no

I've configured eslint to alert me about unused variables

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

Presently, I have a TypeScript class structured like this:

import { User } from './user';

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

Upon running eslint, I encounter the following error message:

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

I'm puzzled by eslint's warning. To me, it seems like the variable is being utilized.

typescript eslint

Answer 1

Answer №1

When looking at the example provided, it's important to note that the type Promise is used to define a type and not necessarily indicate that User is being used in your Method. Eslint expectations are as follows:

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
  }
}

In this case, your Eslint rule will only apply to the User object and not the interface.

For further information, you may refer to:

Answer 2

When looking at the example provided, it's important to note that the type Promise is used to define a type and not necessarily indicate that User is being used in your Method. Eslint expectations are as follows:

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
  }
}

In this case, your Eslint rule will only apply to the User object and not the interface.

For further information, you may refer to:

Answer 3

Answer №2

To prevent inaccurate error reporting, it is recommended to deactivate the base rule. For more information, please refer to: Deactivating Base Rule

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

UserModel.ts

export class UserModel {
    username: string;
}

MyComponent.ts

import { UserModel } from './UserModel'

export class MyComponent {
    async myFunction(): Promise<UserModel> {
        // Some code here
    }
}

Below is a simplified version of my eslint configuration

module.exports = {
  "parser": "@typescript-eslint/parser",
  "plugins": ["@typescript-eslint/eslint-plugin"],
  "env": {
    "node": true
  },
  "extends": "eslint:recommended",
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module"
  },
  "rules": {
    "no-unused-vars": "off",
    "@typescript-eslint/no-unused-vars": ['error'],
  }
}

dependencies in package.json

{
  "scripts": {
    "lint": "eslint app.ts"
  },
  "devDependencies": {
    "@types/eslint": "7.2.4",
    "@types/node": "13.7.7",
    "@typescript-eslint/eslint-plugin": "4.14.1",
    "@typescript-eslint/parser": "4.14.1",
    "eslint": "7.18.0",
    "ts-node": "8.6.2",
    "typescript": "3.8.3"
  }
}

Answer 4

To prevent inaccurate error reporting, it is recommended to deactivate the base rule. For more information, please refer to: Deactivating Base Rule

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

UserModel.ts

export class UserModel {
    username: string;
}

MyComponent.ts

import { UserModel } from './UserModel'

export class MyComponent {
    async myFunction(): Promise<UserModel> {
        // Some code here
    }
}

Below is a simplified version of my eslint configuration

module.exports = {
  "parser": "@typescript-eslint/parser",
  "plugins": ["@typescript-eslint/eslint-plugin"],
  "env": {
    "node": true
  },
  "extends": "eslint:recommended",
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module"
  },
  "rules": {
    "no-unused-vars": "off",
    "@typescript-eslint/no-unused-vars": ['error'],
  }
}

dependencies in package.json

{
  "scripts": {
    "lint": "eslint app.ts"
  },
  "devDependencies": {
    "@types/eslint": "7.2.4",
    "@types/node": "13.7.7",
    "@typescript-eslint/eslint-plugin": "4.14.1",
    "@typescript-eslint/parser": "4.14.1",
    "eslint": "7.18.0",
    "ts-node": "8.6.2",
    "typescript": "3.8.3"
  }
}

Eslint is back and it's cracking down on unused variables with no

Answer №1

Answer №2

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