.eslintrc.json

{
  "plugins": ["eslint-comments", "promise", "unicorn"],
  "extends": [
    "airbnb",
    "airbnb/hooks",
    "plugin:eslint-comments/recommended",
    "plugin:promise/recommended",
    "plugin:unicorn/recommended",
    "prettier",
    "next"
  ],
  "env": {
    "browser": true,
    "node": true
  },
  "settings": {
    "react": {
      "version": "detect"
    }
  },
  "parserOptions": {
    "project": "./tsconfig.json",
    "ecmaVersion": 13,
    "sourceType": "module",
    "ecmaFeatures": {
      "jsx": true
    }
  },
  "rules": {
    // React is already in-scope for all files compiled with Next.js
    "react/react-in-jsx-scope": "off",
    // SSR does not support useLayoutEffect
    "no-restricted-imports": [
      "error",
      {
        "name": "react",
        "importNames": ["useLayoutEffect"],
        "message": "`useLayoutEffect` causes a warning in SSR. Use `useEffect`"
      }
    ],
    // Enables for of and for in loops since airbnb does not allow them
    "no-restricted-syntax": "off",
    // Enforces camelcase
    "camelcase": [
      "error",
      {
        "ignoreDestructuring": true
      }
    ],
    // Too restrictive, writing ugly code to defend against a very unlikely scenario: https://eslint.org/docs/rules/no-prototype-builtins
    "no-prototype-builtins": "off",
    // Does not allow unreachable loops unless its a for of loop
    "no-unreachable-loop": ["error", { "ignore": ["ForInStatement", "ForOfStatement"] }],
    // The default case may not be necessary when explicitly knowing return types
    "default-case": "warn",
    // Can make ugly code
    "consistent-return": "off",
    // Can make ugly code
    "no-case-declarations": "off",
    // Too restrictive: https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/destructuring-assignment.md
    "react/destructuring-assignment": "off",
    // No jsx extension: https://github.com/facebook/create-react-app/issues/87#issuecomment-234627904
    "react/jsx-filename-extension": "off",
    // Allow only arrow function based components
    "react/function-component-definition": [2, { "namedComponents": "arrow-function" }],
    // Common practice in React
    "react/jsx-props-no-spreading": "off",
    // Warn when the index is used as a key instead of a unique value
    "react/no-array-index-key": "warn",
    // Sometimes its useful to return a useless fragment instead of adding a null as a union type
    "react/jsx-no-useless-fragment": "warn",
    // Common abbreviations are known and readable
    "unicorn/prevent-abbreviations": "off",
    // Airbnb prefers forEach
    "unicorn/no-array-for-each": "off",
    // React prefers capitalized file names for components
    "unicorn/filename-case": "off",
    // Enables Array.reduce()
    "unicorn/no-array-reduce": "off",
    // https://basarat.gitbooks.io/typescript/docs/tips/defaultIsBad.html
    "import/prefer-default-export": "off",
    // It's not accurate in the monorepo style
    "import/no-extraneous-dependencies": "off",
    // Import for import of components
    "import/no-cycle": "off"
  },
  "overrides": [
    {
      "files": ["**/*.js"],
      "rules": {
        // Allow CJS until ESM support improves
        "unicorn/prefer-module": "off"
      }
    },
    {
      "files": ["**/*.ts", "**/*.tsx"],
      "plugins": ["@typescript-eslint"],
      "extends": [
        "airbnb-typescript",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/recommended-requiring-type-checking"
      ],
      "parser": "@typescript-eslint/parser",
      "rules": {
        // It's not accurate in the monorepo style
        "import/no-extraneous-dependencies": "off",
        // Requires return type
        "@typescript-eslint/explicit-function-return-type": "error",
        // Allows the use of functions before definition
        "@typescript-eslint/no-use-before-define": ["off"],
        // Allows variables starting with _ to be ignored if not used
        "@typescript-eslint/no-unused-vars": [
          "error",
          {
            "argsIgnorePattern": "^_"
          }
        ],
        // Disallows function overloading
        "@typescript-eslint/unified-signatures": "error",
        // Requires function return types
        "@typescript-eslint/prefer-function-type": "error",
        // Requires classes to make member access explicit
        "@typescript-eslint/explicit-member-accessibility": "error",
        // Requires the use of interface over type when possible
        "@typescript-eslint/consistent-type-definitions": "error",
        // Requires consistent type casting
        "@typescript-eslint/consistent-type-assertions": "error",
        // Requires the T[] type syntax for an array
        "@typescript-eslint/array-type": "error",
        // Next.js does not require all anchor tags to have an href
        "jsx-a11y/anchor-is-valid": "off"
      }
    }
  ]
}