.eslintrc.json

{
  "env": {
    "es2021": true,
    "jest": true,
    "node": true
  },
  "extends": ["eslint:recommended"],

  "parserOptions": {
    "ecmaVersion": "latest",
    "sourceType": "module"
  },
  "rules": {
    "linebreak-style": [
      "error",
      "unix"
    ],
    "prefer-const": [
      "error",
      {
        "destructuring": "all"
      }
    ],
    "no-var": "error",
    "no-new-object": "error",
    "no-new-wrappers": "error",
    "quote-props": [
      "error",
      "as-needed"
    ],
    "no-array-constructor": "error",
    "object-shorthand": [
      "error",
      "properties"
    ],
    "prefer-destructuring": [
      "warn",
      {
        "VariableDeclarator": {
          "array": true,
          "object": true
        },
        "AssignmentExpression": {
          "array": false,
          "object": true
        }
      }
    ],
    "quotes": [
      "error",
      "single"
    ],
    "prefer-template": "off",
    "template-curly-spacing": [
      "warn",
      "never"
    ],
    "prefer-rest-params": "error",
    "wrap-iife": [
      "error",
      "outside"
    ],
    "no-loop-func": "error",
    "no-new-func": "error",
    "func-style": [
      "error",
      "declaration",
      {
        "allowArrowFunctions": true
      }
    ],
    "space-before-function-paren": [
      "error",
      "always"
    ],
    "space-before-blocks": [
      "error",
      {
        "functions": "always"
      }
    ],
    "no-param-reassign": [
      "warn",
      {
        "props": false
      }
    ],
    "prefer-spread": "error",
    "prefer-arrow-callback": [
      "error",
      {
        "allowNamedFunctions": true
      }
    ],
    "arrow-spacing": "error",
    "arrow-parens": [
      "error",
      "as-needed"
    ],
    "no-confusing-arrow": [
      "error",
      {
        "allowParens": true
      }
    ],
    "no-iterator": "error",
    "no-restricted-syntax": [
      "error",
      "WithStatement",
      "BinaryExpression[operator='in']",
      {
        "selector": "CallExpression[callee.name='setTimeout'][arguments.length!=2]",
        "message": "setTimeout must always be invoked with two arguments."
      }
    ],
    "generator-star-spacing": [
      "error",
      {
        "before": false,
        "after": false
      }
    ],
    "dot-notation": "error",
    "no-undef": [
      "error",
      {
        "typeof": false
      }
    ],
    "no-multi-assign": "error",
    "no-multi-spaces": "warn",
    "no-plusplus": [
      "error",
      {
        "allowForLoopAfterthoughts": true
      }
    ],
    "max-len": [
      "off",
      {
        "code": 80,
        "ignoreComments": true,
        "ignoreTrailingComments": true
      }
    ],
    "eqeqeq": "warn",
    "no-case-declarations": "warn",
    "no-nested-ternary": "error",
    "no-unneeded-ternary": "error",
    "no-mixed-operators": [
      "error",
      {
        "groups": [
          [
            "&",
            "|",
            "^",
            "~",
            "<<",
            ">>",
            ">>>"
          ],
          [
            "&&",
            "||"
          ],
          [
            "==",
            "!=",
            "===",
            "!==",
            ">",
            ">=",
            "<",
            "<="
          ]
        ],
        "allowSamePrecedence": true
      }
    ],
    "nonblock-statement-body-position": [
      "error",
      "beside"
    ],
    "no-else-return": "error",
    "spaced-comment": [
      "error",
      "always",
      {
        "block": {
          "balanced": true
        }
      }
    ],
    "indent": [
      "error",
      2
    ],
    "semi-spacing": [
      "error",
      {
        "before": false,
        "after": true
      }
    ],
    "comma-spacing": [
      "error",
      {
        "before": false,
        "after": true
      }
    ],
    "comma-dangle": [
      "error",
      "always-multiline"
    ],
    "space-infix-ops": "error",
    "camelcase": "off",
    "keyword-spacing": "error",
    "no-fallthrough": "off",
    "curly": "off",
    "semi": [
      "error",
      "never"
    ],
    "no-empty": "off",
    "no-alert": "warn",
    "no-class-assign": "off",
    "no-useless-escape": "off",
    "no-bitwise": "off",
    "no-eq-null": "off",
    "no-debugger": "error",
    "guard-for-in": "warn",
    "object-curly-spacing": [
      "error",
      "always"
    ]
  },

  "overrides": [
    // Match TypeScript Files
    // =================================
    {
      "files": ["**/*.{ts,tsx}"],

      // Global ESLint Settings
      // =================================
      "env": {
        "jest": true,
        "node": true
      },
      "settings": {
        "import/parsers": {
          "@typescript-eslint/parser": [".ts", ".tsx"]
        },
        "import/resolver": {
          "typescript": {
            "project": "./tsconfig.json"
          }
        }
      },

      // Parser Settings
      // =================================
      // allow ESLint to understand TypeScript syntax
      // https://github.com/iamturns/eslint-config-airbnb-typescript/blob/master/lib/shared.js#L10
      "parser": "@typescript-eslint/parser",
      "parserOptions": {
        // Lint with Type Information
        // https://github.com/typescript-eslint/typescript-eslint/blob/master/docs/getting-started/linting/TYPED_LINTING.md
        "project": "./tsconfig.json"
      },

      // Plugins
      // =================================
      "plugins": ["@typescript-eslint"],

      // Extend Other Configs
      // =================================
      "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/eslint-recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/recommended-requiring-type-checking"
      ],
      "rules": {
        "@typescript-eslint/no-unused-vars": [
          "error",
          {
            "vars": "all",
            "argsIgnorePattern": "^_"
          }
        ],
        // to enforce using type for object type definitions, can be type or interface
        "@typescript-eslint/consistent-type-definitions": ["error", "interface"],
        // temp allowing during TS migration
        "@typescript-eslint/ban-ts-comment": [
          "error",
          {
            "ts-ignore": "allow-with-description",
            "minimumDescriptionLength": 4
          }
        ]
      }
    }
  ]
}