@cybozu/eslint-config/flat/lib/typescript.js

ESLint rules for Cybozu

const tseslint = require("typescript-eslint");
const stylisticTs = require("@stylistic/eslint-plugin-ts");

/**
 * @return { import("eslint").Linter.FlatConfig[] }
 */
module.exports = function typescript() {
  return [
    ...tseslint.configs.recommended,
    ...tseslint.configs.stylistic,
    {
      plugins: {
        "@typescript-eslint": tseslint.plugin,
        "@stylistic/ts": stylisticTs,
      },
      languageOptions: {
        parser: tseslint.parser,
        // It's 5〜10x slower with the project setting.
        // So We disable it until the issue has been fixed
        /*
        parserOptions: {
          project: true,
        },
        */
      },
      rules: {
        "@typescript-eslint/array-type": ["error", { default: "array-simple" }],

        "no-useless-constructor": "off",
        "@typescript-eslint/no-useless-constructor": "warn",
        "@typescript-eslint/unified-signatures": "warn",
        "@stylistic/ts/indent": ["warn", 2, { SwitchCase: 1 }],

        "@typescript-eslint/ban-ts-comment": "off",
        "@typescript-eslint/explicit-member-accessibility": "off",
        "@typescript-eslint/no-explicit-any": "off",
        "@typescript-eslint/no-empty-interface": "off",
        "@typescript-eslint/no-inferrable-types": "off",
        "@typescript-eslint/no-object-literal-type-assertion": "off",
        "@typescript-eslint/no-triple-slash-reference": "off",
        "@typescript-eslint/no-unused-vars": "off",
        "@typescript-eslint/prefer-interface": "off",

        "no-shadow": "off",
        "@typescript-eslint/no-shadow": "error",

        // These rules are required type information,
        // which means these can be checked without parserOptions.project
        // "@typescript-eslint/no-for-in-array": "error",
        // "@typescript-eslint/no-unnecessary-type-assertion": "warn",

        // These rules are temporarily set to maintain compatibility with v5.
        // To delete as appropriate when reviewing the adaptation rules again.
        // rules removed from `recommended` in v6
        "no-extra-semi": "off",
        "@stylistic/ts/no-extra-semi": "error",
        // rules moved to `strict` in v6
        "@typescript-eslint/no-non-null-assertion": "warn",
        // rules added to `recommended` in v6
        "@typescript-eslint/no-duplicate-enum-values": "off",
        "@typescript-eslint/no-unsafe-declaration-merging": "off",
        // `stylistic` rules not moved from v5 `recommended`
        "@typescript-eslint/ban-tslint-comment": "off",
        "@typescript-eslint/class-literal-property-style": "off",
        "@typescript-eslint/consistent-generic-constructors": "off",
        "@typescript-eslint/consistent-indexed-object-style": "off",
        "@typescript-eslint/consistent-type-assertions": "off",
        "@typescript-eslint/consistent-type-definitions": "off",
        "@typescript-eslint/no-confusing-non-null-assertion": "off",
        "@typescript-eslint/prefer-for-of": "off",
        "@typescript-eslint/prefer-function-type": "off",

        // rules deleted from `recommended` in v8
        "no-loss-of-precision": "off",
        "@typescript-eslint/no-loss-of-precision": "error",

        // added instead of `@typescript-eslint/ban-types` in v8
        "@typescript-eslint/no-empty-object-type": "error",
        "@typescript-eslint/no-unsafe-function-type": "error",
        "@typescript-eslint/no-wrapper-object-types": "error",

        // rules added to `recommended` in v8
        "@typescript-eslint/no-require-imports": "off",
        "no-unused-expressions": "error",
        "@typescript-eslint/no-unused-expressions": "off",
        "@typescript-eslint/prefer-namespace-keyword": "off",
      },
    },
  ];
};