.eslintrc.json

{
  "root": true,
  "env": {
    "browser": true,
    "node": true,
    "es6": true
  },
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "ecmaFeatures": {
      "jsx": true
    },
    "ecmaVersion": 12,
    "sourceType": "module"
  },
  "extends": [
    "next",
    "eslint:recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:import/recommended",
    "plugin:import/typescript",
    "plugin:playwright/playwright-test",
    "prettier"
  ],
  "plugins": ["@typescript-eslint", "simple-import-sort", "unused-imports", "import"],
  "settings": {
    "import/parsers": {
      "@typescript-eslint/parser": [".ts", ".tsx"]
    },
    "import/resolver": {
      "typescript": {
        "project": "./tsconfig.json"
      }
    }
  },
  "rules": {
    // ESLint rules
    "no-implicit-coercion": "error", // use shorter, more self-explanatory notation for the type conversion

    // Next rules
    "@next/next/no-img-element": "off", // We currently not using next/image because it isn't supported with SSG mode

    // React rules
    "react-hooks/rules-of-hooks": "error",
    "react-hooks/exhaustive-deps": "error",
    "react/jsx-props-no-spreading": "off", // _app.tsx uses spread operator
    "react/destructuring-assignment": "off", // Vscode doesn't support automatically destructuring, it's a pain to add a new variable

    // TypeScript rules
    "@typescript-eslint/no-unused-vars": "off", // duplicate option "unused-imports/no-unused-vars"
    "@typescript-eslint/array-type": ["error", { "default": "array-simple" }],
    "@typescript-eslint/consistent-type-imports": "error", // Ensure `import type` is used when it's necessary
    "@typescript-eslint/comma-dangle": "off", // Avoid conflict rule between Eslint and Prettier
    "@typescript-eslint/naming-convention": [
      "error",
      {
        "format": ["camelCase", "UPPER_CASE", "PascalCase"],
        "selector": "variable",
        "leadingUnderscore": "allow"
      },
      { "format": ["camelCase", "PascalCase"], "selector": "function" },
      { "format": ["PascalCase"], "selector": "interface" },
      { "format": ["PascalCase"], "selector": "typeAlias" }
    ],

    // Default import rules
    "import/no-unresolved": "error",
    "import/prefer-default-export": "off", // Named export is easier to refactor automatically

    // Simple import recommended rules
    "simple-import-sort/imports": [
      "error",
      {
        "groups": [
          // react > next > @ > a~z
          ["^react$", "^next", "^@", "^[a-z]"],
          // ~
          ["^~"],
          // `../` > './'
          ["^\\.\\.(?!/?$)", "^\\.\\./?$", "^\\./(?=.*/)(?!/?$)", "^\\.(?!/?$)", "^\\./?$"],
          // Side effect imports
          ["^\\u0000"]
        ]
      }
    ],
    "simple-import-sort/exports": "error",
    "import/first": "error", // makes sure all imports are at the top of the file. (autofixable)
    "import/newline-after-import": "error", // makes sure there’s a newline after the imports. (autofixable)
    "import/no-duplicates": "error", // merges import statements of the same file. (autofixable, mostly)

    // Unused import recommended rules
    "unused-imports/no-unused-imports": "warn",
    "unused-imports/no-unused-vars": [
      "warn",
      {
        "vars": "all",
        "varsIgnorePattern": "^_",
        "args": "after-used",
        "argsIgnorePattern": "^_"
      }
    ]
  },
  "overrides": [
    {
      "env": {
        "jest": true
      },
      "files": ["**/__tests__/**/*.[jt]s?(x)"],
      "extends": [
        "plugin:testing-library/react",
        "plugin:jest/recommended",
        "plugin:jest-dom/recommended"
      ]
    }
  ]
}