.eslintrc.json

{
  "root": true,
  "extends": [
    "plugin:@cspell/recommended",

    // Display Prettier errors as ESLint errors.
    // Enables eslint-plugin-prettier and eslint-config-prettier.
    "plugin:prettier/recommended"

    //! Prettier should always be the last configuration in the extends array.
  ],
  "overrides": [
    /*
     * Typescript files.
     */
    {
      "files": ["*.ts"],
      "parser": "@typescript-eslint/parser",
      "env": {
        "node": true,
        "jest": true
      },
      "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/recommended-requiring-type-checking",
        "plugin:@typescript-eslint/strict",
        "plugin:eslint-plugin/recommended",
        "plugin:security/recommended",

        // Display Prettier errors as ESLint errors.
        // Enables eslint-plugin-prettier and eslint-config-prettier.
        "plugin:prettier/recommended"

        //! Prettier should always be the last configuration in the extends array.
      ],
      "plugins": ["@typescript-eslint", "eslint-plugin"],
      "parserOptions": {
        "project": ["./tsconfig.json"]
      },
      "rules": {
        "@typescript-eslint/array-type": ["error", { "default": "generic" }],
        "@typescript-eslint/consistent-type-imports": "error",
        "@typescript-eslint/explicit-function-return-type": "error",
        "@typescript-eslint/no-unused-vars": [
          "error",
          {
            "argsIgnorePattern": "_"
          }
        ],

        "eslint-plugin/consistent-output": ["error", "always"],
        "eslint-plugin/meta-property-ordering": "error",
        "eslint-plugin/prefer-placeholders": "error",
        "eslint-plugin/prefer-replace-text": "error",
        "eslint-plugin/report-message-format": [
          "error",
          "^[A-Z].*(`{{prop}}`).*\\.$"
        ], // Must start with capital, end with period and contains placeholder for "prop".
        "eslint-plugin/require-meta-docs-description": "error",
        "eslint-plugin/require-meta-docs-url": "off", // This is handled by `ESLintUtils.RuleCreator`.
        "eslint-plugin/test-case-property-ordering": [
          "error",
          ["name", "code", "options"]
        ],
        "eslint-plugin/test-case-shorthand-strings": ["error", "consistent"]
      }
    },

    /*
     * JSON files.
     */
    {
      "files": ["*.json"],
      "extends": [
        "plugin:json/recommended-with-comments",

        // Display Prettier errors as ESLint errors.
        // Enables eslint-plugin-prettier and eslint-config-prettier.
        "plugin:prettier/recommended"

        //! Prettier should always be the last configuration in the extends array.
      ]
    },

    /*
     * `package.json` file.
     * This needs it's own configuration, because it doesn't work together with `plugin:json`.
     * See https://github.com/kellyselden/eslint-plugin-json-files/issues/40
     * Must be after `*.json`.
     */
    {
      "files": ["package.json"],
      "plugins": ["json-files"],
      "extends": [
        // Display Prettier errors as ESLint errors.
        // Enables eslint-plugin-prettier and eslint-config-prettier.
        "plugin:prettier/recommended"

        //! Prettier should always be the last configuration in the extends array.
      ],
      "rules": {
        "json-files/ensure-repository-directory": "error",
        "json-files/no-branch-in-dependencies": "error",
        "json-files/require-engines": "error",
        "json-files/require-license": "error",
        "json-files/require-unique-dependency-names": "error",
        "json-files/sort-package-json": "error"
      }
    },

    /*
     * Markdown files.
     */
    {
      "files": ["*.md"],
      "parser": "eslint-plugin-markdownlint/parser",
      "extends": [
        "plugin:markdownlint/recommended",

        // Display Prettier errors as ESLint errors.
        // Enables eslint-plugin-prettier and eslint-config-prettier.
        "plugin:prettier/recommended"

        //! Prettier should always be the last configuration in the extends array.
      ],
      "rules": {
        "markdownlint/md013": "off", // Disable line length.
        "markdownlint/md033": ["error", { "allowed_elements": ["br"] }], // Allow br-element.
        "prettier/prettier": ["error", { "parser": "markdown" }]
      }
    }
  ]
}