.eslintrc.json

{
  "env": {
    "browser": false,
    "commonjs": true,
    "es2021": true,
    "jest": true,
    "node": true
  },
  "extends": "eslint:recommended",
  "parserOptions": {
    "ecmaVersion": "latest"
  },
  "rules": {
    "no-console": "off",
    //* Avoid Bugs
    "no-undef": "error",
    "semi": "error",
    "semi-spacing": "error",
    //* Best Practices
    "eqeqeq": "warn",
    "no-invalid-this": "error",
    "no-return-assign": "error",
    "no-unused-expressions": [
      "error",
      {
        "allowTernary": true
      }
    ],
    "no-useless-concat": "error",
    "no-useless-return": "error",
    "no-constant-condition": "warn",
    "no-unused-vars": [
      "warn",
      {
        "argsIgnorePattern": "req|res|next|__"
      }
    ],
    //* Enhance Readability
    //* "indent": ["error", 2, {"SwitchCase": 1}],
    "no-mixed-spaces-and-tabs": "warn",
    "space-before-blocks": "error",
    "space-in-parens": "error",
    "space-infix-ops": "error",
    "space-unary-ops": "error",
    "quotes": [
      "error",
      "single"
    ],
    "semi-style": "error",
    //
    "max-len": [
      "error",
      {
        "code": 200
      }
    ],
    "max-lines": [
      "error",
      {
        "max": 500
      }
    ],
    "keyword-spacing": "error",
    "multiline-ternary": [
      "error",
      "never"
    ],
    "no-mixed-operators": "error",
    //
    "no-multiple-empty-lines": [
      "error",
      {
        "max": 2,
        "maxEOF": 1
      }
    ],
    "no-whitespace-before-property": "error",
    "nonblock-statement-body-position": "error",
    "object-property-newline": [
      "error",
      {
        "allowAllPropertiesOnSameLine": true
      }
    ],
    //* ES6
    "arrow-spacing": "error",
    "no-confusing-arrow": "error",
    "no-duplicate-imports": "error",
    "no-var": "error",
    "object-shorthand": "off",
    "prefer-const": "error",
    "prefer-template": "warn"
  }
}