Eslint Typescript "No Implicit Any" rule

Question

I am setting up a new typescript project with eslint. I am trying to setup eslint rules correctly so that the tsc command runs without errors. I have the problem with the "noImplicitAny" rule, which I use in tsconfig.json , but I am unable check for this in eslint.

.eslintrc.js:

module.exports = {
    extends: [
        "eslint:recommended",
        "plugin:@typescript-eslint/eslint-recommended",
        "plugin:@typescript-eslint/recommended",
    ],
    parser: "@typescript-eslint/parser",
    parserOptions: {
        project: ["tsconfig.json"],
        sourceType: "module",
    },
    rules: {
        "no-undef": "warn",
    },
    plugins: ["@typescript-eslint"],
    settings: {
        "import/resolver": {
            node: {
                extensions: [".js", ".ts"],
            },
        },
    },
};

tsconfig.json:

{
  "compilerOptions": {
    "target": "es5",
    "module": "ES6",
    "declaration": true,
    "outDir": "./lib",
    "strict": true,
    "noImplicitAny": true
  },
  "include": ["src/**/*.ts"],
  "exclude": ["node_modules", "**/__tests__/*"]
}

In short I want the eslint to check for the implicit any and warn about its usage. How can I configure the rules in .eslintrc.js to achieve this?

Answer 1

There are a number of no-unsafe-* rules that have been implemented in TypeScript-ESLint:

• no-unsafe-call - forbids calling an expression typed as any
• no-unsafe-member-access - forbids using any as a member name
• no-unsafe-argument - forbids passing any as a function parameter
• no-unsafe-assignment - forbids using any in an assignment

On a similar note, there's no-explicit-any . Put all of these together, and you should be fully protected against any problems.

Answer 2

eslint refuses to add a no-implicit-any due to the fact it duplicates a typescript rule.

They did however make a transition rule that should not be used permanently which does what you wanted. You should remove this rule once you can turn these options on in your tsconfig file.

This allows warning for implicit parameters or arguments in normal and arrow functions. There are more options than the ones commented out, documentation linked below.

    '@typescript-eslint/typedef': [
      'warn',
      {
        parameter: true,
        arrowParameter: true,
        // variableDeclaration: true,
        // memberVariableDeclaration: true,
        // objectDestructuring: true,
      },
    ],

link to github issue not allowing no-implicit-any https://github.com/typescript-eslint/typescript-eslint/issues/3979

doucmentation for typedef information https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/eslint-plugin/docs/rules/typedef.md