ESLint - "no-unused-vars" on function parameters within TypeScript Types/Interfaces

Question

I am currently getting a eslint warning on function parameters within Types or Interfaces.

Doing the following:

type Test = {
  fn: (param: string) => void
}

Results in the following warning:

'param' is defined but never used. Allowed unused args must match /^_/u.

Here's what my .eslintrc.json looks like:

{
  "root": true,
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "project": "tsconfig.json"
  },
  "env": {
    "node": true
  },
  "plugins": ["@typescript-eslint"],
  "extends": [
    "eslint:recommended",
    "plugin:@typescript-eslint/eslint-recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:prettier/recommended"
  ],
  "rules": {
    "@typescript-eslint/interface-name-prefix": "off",
    "@typescript-eslint/explicit-function-return-type": "off",
    "@typescript-eslint/explicit-module-boundary-types": "off"
  }
}

Package versions:

"eslint": "^7.23.0"
"@typescript-eslint/eslint-plugin": "^4.22.1"
"@typescript-eslint/parser": "^4.22.1"

Similar questions have been asked already here and here, but the provided answers do not seem to be doing it for me.

Any suggestions as to what could be happening?

Answer 1

I've solved it this way, put these two lines in rules in the eslint configuration file.

"no-unused-vars": "off",
"@typescript-eslint/no-unused-vars": ["error"]

Answer 2

You can configure the no-unused-vars rule to ignore arguments named param by adding this line to your .eslintrc.json rules: "no-unused-vars": ["error", { "argsIgnorePattern": "params"}]. See the docs: https://eslint.org/docs/latest/rules/no-unused-vars#argsignorepattern