.eslintrc.cjs

// eslint-disable-next-line no-undef
module.exports = {
  parser: "@typescript-eslint/parser",
  plugins: ["@typescript-eslint", "jsdoc", "eslint-plugin-tsdoc", "no-null", "import", "unused-imports"],
  root: true,
  ignorePatterns: [
    // Ignore compiled JavaScript files (old build setup, changed on 2023-05-04 to _build to src/_.
    "dist/",
    "docs/",
    "node_modules/",
    "typings/",
    "*.orig",
    // Ignore compiled JavaScript files, as they are generated automatically.
    "**/src/**/*.js",
    // Also, do not check typing declarations, too.
    "**/src/**/*.d.ts",
  ],
  overrides: [
    {
      files: ["**/*.{js,cjs,mjs,ts,tsx}"],
      extends: [
        // Prettier recommended for formatting rules: https://typescript-eslint.io/docs/linting/configs/#prettier
        "prettier",
        "plugin:prettier/recommended", // Enables eslint-plugin-prettier and displays prettier errors as ESLint errors. Make sure this is always the last configuration in the extends array.
      ],
      rules: {
        "prettier/prettier": "error",
      },
    },
    {
      files: ["**/*.js"],
      extends: ["eslint:recommended"],
    },
    {
      files: ["**/*.config.{js,cjs,mjs}", "**/*.local.{js,cjs,mjs}", "**/*rc.{js,cjs,mjs}"],
      rules: {
        "no-undef": "off",
        "no-unused-vars": "off",
      },
    },
    {
      files: ["**/*.{ts,tsx}"],
      extends: [
        "eslint:recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/recommended-requiring-type-checking",
        "plugin:@typescript-eslint/strict",
        "plugin:jsdoc/recommended",
      ],
      rules: {
        /*
         * =====================================================================
         * TypeScript/Broken Window
         *
         * Possibly fix later or adjust configuration. Prefer adding exclusions
         * to corresponding modules. As soon as multiple modules are affected,
         * add them to this configuration. Exception: If you consider a
         * violation to be addressed as soon as possible and only a few
         * modules are affected, duplicate the exclusions only in affected
         * modules.
         * =====================================================================
         */
        // Broken Window/ESLint
        "no-prototype-builtins": "off",
        /*
         * =====================================================================
         * Vetoed Rules
         * =====================================================================
         */
        // While some results may be valid, others need much more careful
        // review, not to break the application. Some issues may be a result
        // of bad typings. If we enable it, results must be reviewed carefully.
        "@typescript-eslint/no-unnecessary-condition": "off",
        // Collides with @typescript-eslint/no-non-null-assertion at several
        // places. Possibly obsolete to suppress, if we refactor for example
        // AttributesMap to some real Map rather than just a Record.
        "@typescript-eslint/non-nullable-type-assertion-style": "off",
        // Possibly useful, but requires a lot of effort to get straight.
        // If we see, this is an issue with `[object Object]` and similar in
        // strings, we may want to address that explicitly.
        "@typescript-eslint/restrict-template-expressions": "off",
        // While this may provide valid issues, it often clashes with
        // the common localization pattern of CKEditor 5, i.e., accessing
        // editor.locale.t. Ignored for now, unless we find a better option.
        "@typescript-eslint/unbound-method": "off",
        // While misuse of empty tags having contents seems to be a good
        // idea, it collides with TypeDoc, expecting @inheritDoc with
        // some argument. Unfortunately, there is no exclusion but only
        // inclusion mechanism for this rule.
        "jsdoc/empty-tags": "off",
        // Not relevant for TypeScript.
        "jsdoc/no-undefined-types": "off",
        // Collides with `@example` syntax for TypeDoc. May be possibly
        // fine-tuned by more explicit configuration.
        "jsdoc/tag-lines": "off",
        /*
         * =====================================================================
         * ESLint
         * =====================================================================
         */
        "arrow-body-style": ["error", "as-needed"],
        "consistent-return": "error",
        "constructor-super": "error",
        "curly": ["error", "multi-line"],
        "dot-notation": "error",
        "eqeqeq": "error",
        "import/no-duplicates": "error",
        // linebreak-style: First needs to be fixed on Windows.
        "linebreak-style": ["off", "windows"],
        "max-statements-per-line": ["error", { max: 1 }],
        "new-parens": "error",
        "no-caller": "error",
        "no-duplicate-case": "error",
        "no-empty": "error",
        "no-eval": "error",
        "no-extra-bind": "error",
        "no-extra-boolean-cast": "error",
        "no-fallthrough": "error",
        "no-new-func": "error",
        "no-new-wrappers": "error",
        "no-return-await": "error",
        "no-restricted-globals": [
          "error",
          { name: "setTimeout" },
          { name: "clearTimeout" },
          { name: "setInterval" },
          { name: "clearInterval" },
          { name: "setImmediate" },
          { name: "clearImmediate" },
        ],
        // https://github.com/typescript-eslint/typescript-eslint/issues/1391#issuecomment-1124154589
        "no-restricted-syntax": [
          "error",
          {
            // kind="method": Don't apply on constructors.
            selector: ':matches(PropertyDefinition, MethodDefinition[kind="method"])[accessibility="private"]',
            message: "Use #private instead",
          },
        ],
        "no-sparse-arrays": "error",
        "no-template-curly-in-string": "error",
        "no-throw-literal": "error",
        "no-trailing-spaces": "error",
        "no-undef-init": "error",
        "no-unsafe-finally": "error",
        "no-unused-labels": "error",
        "no-useless-escape": "error",
        "no-var": "error",
        "object-shorthand": "error",
        "prefer-arrow-callback": "error",
        "prefer-const": "error",
        "prefer-object-spread": "error",
        "quote-props": ["error", "consistent-as-needed"],
        "space-in-parens": "error",
        "unicode-bom": ["error", "never"],
        "use-isnan": "error",
        "unused-imports/no-unused-imports": "error",
        /*
         * =====================================================================
         * ESLint Plugin: Import
         * =====================================================================
         */
        "import/no-extraneous-dependencies": ["error", { optionalDependencies: false, devDependencies: true }],
        /*
         * =====================================================================
         * ESLint Plugin: JSDoc
         * =====================================================================
         */
        "jsdoc/check-alignment": "error",
        "jsdoc/check-param-names": "error",
        "jsdoc/check-tag-names": [
          "error",
          {
            definedTags: ["category", "packageDocumentation", "typeParam"],
          },
        ],
        // allowWhitespace: Must be true not to collide with Markdown.
        "jsdoc/no-multi-asterisks": ["error", { allowWhitespace: true }],
        "jsdoc/require-jsdoc": "error",
        // We believe, that if parameters are not described, it is for good
        // reason (like self-explaining parameters).
        "jsdoc/require-param": "off",
        // Collides with TypeScript.
        "jsdoc/require-param-type": "off",
        // We believe, that if return values are not described, it is for good
        // reason (like self-explaining return value).
        "jsdoc/require-returns": "off",
        // Collides with TypeScript.
        "jsdoc/require-returns-type": "off",
        // Collides with TypeScript.
        "jsdoc/valid-types": "off",
        /*
         * =====================================================================
         * ESLint Plugin: No-Null
         * =====================================================================
         */
        "no-null/no-null": "error",
        /*
         * =====================================================================
         * ESLint Plugin: TypeScript
         * =====================================================================
         */
        "@typescript-eslint/adjacent-overload-signatures": "error",
        "@typescript-eslint/array-type": "error",
        "@typescript-eslint/ban-ts-comment": "error",

        "brace-style": "off",
        "@typescript-eslint/brace-style": ["error", "1tbs", { allowSingleLine: true }],

        "@typescript-eslint/consistent-generic-constructors": "error",
        "@typescript-eslint/consistent-indexed-object-style": "error",
        "@typescript-eslint/consistent-type-assertions": ["error", { assertionStyle: "as" }],
        "@typescript-eslint/consistent-type-definitions": ["error", "interface"],

        "@typescript-eslint/naming-convention": [
          "error",
          {
            selector: "typeLike",
            format: ["PascalCase"],
            filter: { regex: "^(__String|[A-Za-z]+_[A-Za-z]+)$", match: false },
          },
          {
            selector: "interface",
            format: ["PascalCase"],
            custom: { regex: "^I[A-Z]", match: false },
            filter: { regex: "^I(Arguments|TextWriter|O([A-Z][a-z]+[A-Za-z]*)?)$", match: false },
          },
          {
            selector: "variable",
            format: ["camelCase", "PascalCase", "UPPER_CASE"],
            leadingUnderscore: "allow",
            filter: { regex: "^(_{1,2}filename|_{1,2}dirname|_+|[A-Za-z]+_[A-Za-z]+)$", match: false },
          },
          {
            selector: "function",
            format: ["camelCase", "PascalCase"],
            leadingUnderscore: "allow",
            filter: { regex: "^[A-Za-z]+_[A-Za-z]+$", match: false },
          },
          {
            selector: "parameter",
            format: ["camelCase"],
            leadingUnderscore: "allow",
            filter: { regex: "^(_+|[A-Za-z]+_[A-Z][a-z]+)$", match: false },
          },
          {
            selector: "method",
            format: ["camelCase", "PascalCase"],
            leadingUnderscore: "allow",
            filter: { regex: "^([0-9]+|[A-Za-z]+_[A-Za-z]+)$", match: false },
          },
          {
            selector: "memberLike",
            format: ["camelCase"],
            leadingUnderscore: "allow",
            filter: { regex: "^([0-9]+|[A-Za-z]+_[A-Za-z]+)$", match: false },
          },
          {
            selector: "enumMember",
            format: ["camelCase", "PascalCase", "UPPER_CASE"],
            leadingUnderscore: "allow",
            filter: { regex: "^[A-Za-z]+_[A-Za-z]+$", match: false },
          },
          { selector: "property", format: null },
        ],

        "@typescript-eslint/no-base-to-string": "error",
        "@typescript-eslint/no-dynamic-delete": "error",
        "@typescript-eslint/no-empty-function": "error",
        "@typescript-eslint/no-extraneous-class": "error",
        "@typescript-eslint/no-inferrable-types": "error",
        "@typescript-eslint/no-invalid-void-type": "error",
        "@typescript-eslint/no-misused-new": "error",
        "@typescript-eslint/no-non-null-assertion": "error",
        // Sometimes a result of composite types, sometimes used for better
        // IDE support, providing hints, such as `"lorem" | string` would
        // propose "lorem" as a possible option.
        "@typescript-eslint/no-redundant-type-constituents": "off",
        "@typescript-eslint/no-this-alias": "error",
        "@typescript-eslint/no-unnecessary-type-assertion": "error",
        "@typescript-eslint/no-unsafe-argument": "error",
        "@typescript-eslint/no-unsafe-assignment": "error",
        "@typescript-eslint/no-unsafe-call": "error",
        "@typescript-eslint/no-unsafe-member-access": "error",
        "@typescript-eslint/no-unsafe-return": "error",

        "no-unused-expressions": "off",
        "@typescript-eslint/no-unused-expressions": ["error", { allowTernary: true, allowShortCircuit: true }],

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

        "@typescript-eslint/no-useless-constructor": "error",
        "@typescript-eslint/prefer-for-of": "error",
        "@typescript-eslint/prefer-function-type": "error",
        "@typescript-eslint/prefer-includes": "error",
        "@typescript-eslint/prefer-namespace-keyword": "error",
        "@typescript-eslint/prefer-nullish-coalescing": ["error", { ignoreConditionalTests: true }],
        "@typescript-eslint/prefer-optional-chain": "error",
        "@typescript-eslint/prefer-readonly": "error",
        "@typescript-eslint/prefer-ts-expect-error": "error",

        "quotes": "off",
        "@typescript-eslint/quotes": ["error", "double", { avoidEscape: true, allowTemplateLiterals: true }],

        "@typescript-eslint/restrict-plus-operands": "error",

        "semi": "off",
        "@typescript-eslint/semi": "error",

        "space-before-function-paren": "off",
        "@typescript-eslint/space-before-function-paren": [
          "error",
          {
            asyncArrow: "always",
            anonymous: "always",
            named: "never",
          },
        ],

        "@typescript-eslint/triple-slash-reference": "error",
        "@typescript-eslint/type-annotation-spacing": "error",
        "@typescript-eslint/unified-signatures": "error",
      },
    },
    /*
     * Test-specific overrides.
     *
     * Some adaptions exist to enable tests to do things, others, because it
     * would make it more complex to write tests, as for example data-driven
     * ones.
     */
    {
      files: ["**/*.test.{ts,tsx}", "**/itest/**/*.{ts,tsx}", "**/__tests__/**/*.{ts,tsx}", "**/*.spec.{ts,tsx}"],
      rules: {
        "no-irregular-whitespace": "off",
        "@typescript-eslint/no-unsafe-argument": "off",
        "@typescript-eslint/no-unsafe-assignment": "off",
        "@typescript-eslint/no-unsafe-call": "off",
        "@typescript-eslint/no-unsafe-member-access": "off",
        "jsdoc/require-jsdoc": "off",
      },
    },
    /*
     * Overrides for example application.
     */
    {
      files: ["app/**/*.{ts,tsx}"],
      rules: {
        "jsdoc/require-jsdoc": "off",
      },
    },
  ],
};