eslint.config.js

// @ts-check

import vitest from "@vitest/eslint-plugin";
import simpleImportSort from "eslint-plugin-simple-import-sort";
import typescriptEslint from "typescript-eslint";
import globals from "globals";
import { builtinModules } from "module";

const error = "error";
const warn = process.argv.includes("--report-unused-disable-directives")
  ? "error"
  : "warn";

const restrictedGlobals = [
  {
    name: "JSON",
    message:
      "Import JSON from tiny-decoders and use its JSON.parse and JSON.stringify with a codec instead.",
  },
];

export default typescriptEslint.config(
  typescriptEslint.configs.base,
  {
    files: ["**/*.ts"],
    plugins: {
      "simple-import-sort": simpleImportSort,
    },
    languageOptions: {
      parserOptions: {
        projectService: true,
        tsconfigRootDir: import.meta.dirname,
      },
    },
    rules: {
      "@typescript-eslint/adjacent-overload-signatures": warn,
      "@typescript-eslint/array-type": [warn, { default: "generic" }],
      "@typescript-eslint/await-thenable": error,
      "@typescript-eslint/ban-ts-comment": error,
      "@typescript-eslint/consistent-generic-constructors": warn,
      "@typescript-eslint/consistent-type-assertions": [
        error,
        {
          assertionStyle: "as",
          objectLiteralTypeAssertions: "never",
        },
      ],
      "@typescript-eslint/consistent-type-definitions": [warn, "type"],
      "@typescript-eslint/default-param-last": warn,
      "@typescript-eslint/explicit-function-return-type": [
        warn,
        { allowExpressions: true },
      ],
      "@typescript-eslint/method-signature-style": warn,
      "@typescript-eslint/no-array-constructor": warn,
      "@typescript-eslint/no-array-delete": error,
      "@typescript-eslint/no-base-to-string": error,
      "@typescript-eslint/no-confusing-void-expression": error,
      "@typescript-eslint/no-deprecated": error,
      "@typescript-eslint/no-dupe-class-members": error,
      "@typescript-eslint/no-duplicate-type-constituents": error,
      "@typescript-eslint/no-empty-function": warn,
      "@typescript-eslint/no-empty-object-type": error,
      "@typescript-eslint/no-explicit-any": warn,
      "@typescript-eslint/no-floating-promises": error,
      "@typescript-eslint/no-for-in-array": warn,
      "@typescript-eslint/no-implied-eval": error,
      "@typescript-eslint/no-inferrable-types": [
        warn,
        { ignoreParameters: true },
      ],
      "@typescript-eslint/no-invalid-this": error,
      "@typescript-eslint/no-invalid-void-type": error,
      "@typescript-eslint/no-misused-promises": error,
      "@typescript-eslint/no-namespace": error,
      "@typescript-eslint/no-non-null-assertion": error,
      "@typescript-eslint/no-redundant-type-constituents": error,
      "@typescript-eslint/no-require-imports": error,
      "@typescript-eslint/no-shadow": error,
      "@typescript-eslint/no-this-alias": warn,
      "@typescript-eslint/no-unnecessary-boolean-literal-compare": warn,
      "@typescript-eslint/no-unnecessary-condition": error,
      "@typescript-eslint/no-unnecessary-parameter-property-assignment": warn,
      "@typescript-eslint/no-unnecessary-template-expression": error,
      "@typescript-eslint/no-unnecessary-type-arguments": warn,
      "@typescript-eslint/no-unnecessary-type-assertion": warn,
      "@typescript-eslint/no-unnecessary-type-constraint": error,
      "@typescript-eslint/no-unnecessary-type-parameters": error,
      "@typescript-eslint/no-unsafe-argument": error,
      "@typescript-eslint/no-unsafe-assignment": error,
      "@typescript-eslint/no-unsafe-call": error,
      "@typescript-eslint/no-unsafe-function-type": error,
      "@typescript-eslint/no-unsafe-member-access": error,
      "@typescript-eslint/no-unsafe-return": error,
      "@typescript-eslint/no-unsafe-unary-minus": error,
      "@typescript-eslint/no-unused-expressions": error,
      "@typescript-eslint/no-unused-vars": [
        error,
        {
          args: "all",
          argsIgnorePattern: "^_",
          varsIgnorePattern: "^_",
          caughtErrors: "all",
          caughtErrorsIgnorePattern: "^_",
        },
      ],
      "@typescript-eslint/no-useless-empty-export": warn,
      "@typescript-eslint/no-wrapper-object-types": error,
      "@typescript-eslint/only-throw-error": error,
      "@typescript-eslint/prefer-as-const": warn,
      "@typescript-eslint/prefer-destructuring": [
        warn,
        { object: true, array: false },
      ],
      "@typescript-eslint/prefer-find": warn,
      "@typescript-eslint/prefer-for-of": warn,
      "@typescript-eslint/prefer-function-type": warn,
      "@typescript-eslint/prefer-includes": warn,
      "@typescript-eslint/prefer-nullish-coalescing": warn,
      "@typescript-eslint/prefer-optional-chain": warn,
      "@typescript-eslint/prefer-reduce-type-parameter": warn,
      "@typescript-eslint/prefer-regexp-exec": warn,
      "@typescript-eslint/prefer-string-starts-ends-with": warn,
      "@typescript-eslint/promise-function-async": [
        error,
        { checkArrowFunctions: false },
      ],
      "@typescript-eslint/require-await": error,
      "@typescript-eslint/restrict-plus-operands": error,
      "@typescript-eslint/restrict-template-expressions": [
        error,
        {
          allowAny: false,
          allowArray: false,
          allowBoolean: false,
          allowNullish: false,
          allowNumber: true,
          allowRegExp: false,
          allowNever: false,
        },
      ],
      "@typescript-eslint/return-await": error,
      "@typescript-eslint/strict-boolean-expressions": [
        error,
        {
          allowString: false,
          allowNumber: false,
          allowNullableObject: false,
        },
      ],
      "@typescript-eslint/switch-exhaustiveness-check": [
        error,
        {
          allowDefaultCaseForExhaustiveSwitch: false,
          requireDefaultForNonUnion: true,
        },
      ],
      "@typescript-eslint/triple-slash-reference": warn,
      "@typescript-eslint/unbound-method": error,
      "@typescript-eslint/unified-signatures": warn,
      "arrow-body-style": warn,
      "default-case-last": warn,
      "for-direction": error,
      "no-caller": error,
      "no-case-declarations": error,
      "no-compare-neg-zero": error,
      "no-console": warn,
      "no-constant-binary-expression": error,
      "no-constant-condition": error,
      "no-debugger": warn,
      "no-dupe-else-if": error,
      "no-duplicate-case": error,
      "no-empty-character-class": warn,
      "no-empty-pattern": warn,
      "no-empty": warn,
      "no-eval": error,
      "no-invalid-regexp": error,
      "no-labels": error,
      "no-loss-of-precision": error,
      "no-misleading-character-class": error,
      "no-nonoctal-decimal-escape": error,
      "no-octal-escape": error,
      "no-param-reassign": error,
      "no-promise-executor-return": error,
      "no-prototype-builtins": error,
      "no-regex-spaces": error,
      "no-restricted-syntax": [
        error,
        {
          selector: "SequenceExpression",
          message:
            "The comma operator is confusing and a common mistake. Don’t use it!",
        },
        {
          selector: `CallExpression[callee.property.name="then"] > :nth-child(2)`,
          message:
            "Use .then(onSuccess).catch(onError) instead of .then(onSuccess, onError)",
        },
      ],
      "no-self-compare": error,
      "no-template-curly-in-string": error,
      "no-unmodified-loop-condition": error,
      "no-unneeded-ternary": warn,
      "no-unsafe-finally": error,
      "no-useless-backreference": error,
      "no-useless-catch": error,
      "no-useless-computed-key": warn,
      "no-useless-concat": warn,
      "no-useless-escape": error,
      "no-useless-rename": warn,
      "no-var": error,
      "object-shorthand": warn,
      "prefer-arrow-callback": warn,
      "prefer-const": warn,
      "prefer-exponentiation-operator": warn,
      "prefer-numeric-literals": warn,
      "prefer-object-spread": warn,
      "prefer-promise-reject-errors": error,
      "prefer-regex-literals": warn,
      "prefer-rest-params": warn,
      "prefer-spread": warn,
      "prefer-template": warn,
      "simple-import-sort/exports": warn,
      "simple-import-sort/imports": warn,
      "use-isnan": error,
      curly: warn,
      eqeqeq: warn,
      yoda: warn,
    },
  },
  {
    files: ["src/**/*.ts", "scripts/**/*.ts"],
    rules: {
      "no-restricted-globals": [
        error,
        ...restrictedGlobals,
        ...Object.keys(globals.browser).filter(
          (name) => !Object.prototype.hasOwnProperty.call(globals.node, name),
        ),
      ],
    },
  },
  {
    files: ["client/**/*.ts"],
    rules: {
      "no-restricted-imports": [error, ...builtinModules],
      "no-restricted-globals": [
        error,
        ...restrictedGlobals,
        ...Object.keys(globals.node).filter(
          (name) =>
            !Object.prototype.hasOwnProperty.call(globals.browser, name),
        ),
      ],
    },
  },
  {
    files: ["tests/**/*.ts"],
    plugins: {
      vitest,
    },
    rules: {
      ...vitest.configs.recommended.rules,
      "vitest/no-disabled-tests": warn,
      "vitest/no-focused-tests": warn,
    },
  },
  {
    ignores: [
      "build",
      "coverage",
      "dist",
      "example",
      "example-minimal",
      "*.d.ts",
      "tests/fixtures",
      "submodules",
    ],
  },
);