.eslintrc.json

{
  "env": { "browser": true, "node": true },
  "extends": [
    "airbnb-base",
    "plugin:@typescript-eslint/recommended",
    "plugin:vitest/recommended",
    "plugin:testing-library/dom",
    "prettier"
  ],
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "ecmaVersion": "latest",
    "sourceType": "module",
    "project": "tsconfig.json"
  },
  "settings": {
    "import/resolver": {
      "node": {
        "extensions": [".js", ".ts", ".d.ts"]
      }
    }
  },
  "rules": {
    // Core Configurations
    "lines-between-class-members": "off",
    "consistent-return": "off", // This is usually annoying, and TS works fine as long as return types are specified.
    "arrow-body-style": "off", // Done because of formatting. Use discretion on which type of function to use.
    "no-unreachable": "error",
    "no-plusplus": ["error", { "allowForLoopAfterthoughts": true }],
    "no-return-assign": ["error", "except-parens"],
    "no-continue": "off", // Useful for keeping conditional logic in `for` loops simpler (similar to early `return`)

    // TypeScript Configurations
    "@typescript-eslint/no-explicit-any": "error",
    "@typescript-eslint/consistent-type-imports": "error",
    "@typescript-eslint/no-unnecessary-condition": "error",
    "@typescript-eslint/strict-boolean-expressions": "off",

    // Core Configurations That Conflict with TS
    "no-undef": "off",
    "no-use-before-define": "off",
    "@typescript-eslint/no-use-before-define": ["error", "nofunc"],
    "no-shadow": "off",
    "@typescript-eslint/no-shadow": "error",
    "default-param-last": "off",
    "@typescript-eslint/default-param-last": "error",
    "no-unused-vars": "off",
    "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }],

    // Import
    "import/extensions": "off", // TypeScript drives which extensions are required (due to `moduleResolution: NodeNext`)
    "import/no-unresolved": "off", // Let TypeScript handle import resolution
    "import/no-extraneous-dependencies": [
      "error",
      {
        "packageDir": [
          "./",
          "packages/core",
          "packages/svelte",
          "packages/vue",
          "packages/solid",
          "packages/react",
          "packages/lit",
          "packages/preact"
        ],
        "peerDependencies": true,
        "devDependencies": ["./vitest.*", "**/*.test.{ts,tsx}"],
        "optionalDependencies": false,
        "bundledDependencies": false
      }
    ],

    // Vitest
    // NOTE: `eslint-plugin-vitest` still has some areas for improvement. So keep an eye out for updates.
    "vitest/no-alias-methods": "error",
    "vitest/no-disabled-tests": "error",
    "vitest/no-focused-tests": "error",
    "vitest/no-interpolation-in-snapshots": "error",
    "vitest/no-mocks-import": "error",
    "vitest/no-test-prefixes": "error",
    "vitest/prefer-to-be": "off"
  },
  "overrides": [
    { "files": "**/utils/*.js", "rules": { "import/prefer-default-export": "off" } },
    {
      "files": "**/__tests__/**/*.test.ts?(x)",
      "rules": {
        "no-await-in-loop": "off",
        "no-restricted-syntax": "off",
        "prefer-promise-reject-errors": "off"
      }
    },
    { "files": "scripts/**/*.js", "rules": { "no-console": "off" } }
  ]
}