lib.js

module.exports = {
  extends: [
    // This profile enables lint rules intended for a
    // web application, for example security rules that are relevant to web browser APIs such as DOM.
    // Also use this profile if you are creating a library that can be consumed by both Node.js and web applications.
    '@rushstack/eslint-config/profile/web-app',
    'prettier/@typescript-eslint', // Uses eslint-config-prettier to disable ESLint rules from @typescript-eslint/eslint-plugin that would conflict with prettier
    'plugin:prettier/recommended', // Enables eslint-plugin-prettier and eslint-config-prettier. This will display prettier errors as ESLint errors. Make sure this is always the last configuration in the extends array.
  ],
  parserOptions: {
    // To include support for Dynamic Imports and BigInt
    // https://eslint.org/blog/2019/08/eslint-v6.2.0-released#highlights-113
    ecmaVersion: 2020,
    // We use ECMAScript modules everywhere
    // (it is set by @rushstack/eslint-config/profile/_common but
    // for some reason we have to set it here again)
    sourceType: 'module',
  },
  // Place to specify ESLint rules. Can be used to
  // overwrite rules specified from the extended configs
  rules: {
    // Place to specify ESLint rules. Can be used to
    // overwrite rules specified from the extended configs
    '@typescript-eslint/explicit-module-boundary-types': 'off',
    // Requiring type annotations unnecessarily can be cumbersome to
    // maintain and generally reduces code readability
    '@typescript-eslint/typedef': 'off',
    // Don't require public accessibiliy modifier
    '@typescript-eslint/explicit-member-accessibility': 'off',
    // Disable the rule for all files
    // (we enable it below for .ts and .tsx files only)
    '@typescript-eslint/explicit-function-return-type': 'off',
    // Allow explit any, lets be pragmatic and honest to ourselves
    '@typescript-eslint/no-explicit-any': 'off',
  },
  // Overrides for a mixed JS/TS codebase,
  // see: https://github.com/typescript-eslint/typescript-eslint/blob/v3.4.0/packages/eslint-plugin/docs/rules/explicit-function-return-type.md#configuring-in-a-mixed-jsts-codebase
  overrides: [
    {
      // Enable rules specifically for TypeScript files
      files: ['*.ts', '*.tsx'],
      rules: {
        // Allow type function expressions and higher order functions to omit return type annotations.
        // Don't require explicit return types in event handlers.
        // https://github.com/typescript-eslint/typescript-eslint/blob/v3.4.0/packages/eslint-plugin/docs/rules/explicit-function-return-type.md
        '@typescript-eslint/explicit-function-return-type': [
          'warn',
          {
            // Type annokktations are also allowed on the
            // variable of a function expression rather than on the function directly
            allowTypedFunctionExpressions: true,
            // Functions immediately returning another function expression will not be checked
            allowHigherOrderFunctions: true,
            // Only functions which are part of a declaration will be checked
            allowExpressions: true,
          },
        ],
      },
    },
  ],
};