.eslintrc.json

{
  "env": {
    "es6": true,
    "browser": true
  },
  "parser": "babel-eslint",
  "parserOptions": {
    "sourceType": "script",
    "ecmaFeatures": {
      "globalReturn": false
    }
  },
  "extends": ["eslint:recommended", "prettier"],
  "rules": {
    "no-console": "warn",
    "no-mixed-spaces-and-tabs": "warn",
    "no-unused-vars": "warn",
    "no-use-before-define": "error",
    "prefer-const": [
      "warn",
      {
        "destructuring": "any",
        "ignoreReadBeforeAssign": true
      }
    ],
    "no-undef": "error",
    "no-redeclare": [2, {"builtinGlobals": false}],
    "indent": ["warn", 4, { "SwitchCase": 1 }],
    "quotes": ["warn", "double", { "avoidEscape": true }],
    "semi": "error",
    "max-len": [
      "warn",
      {
        "code": 120,
        "ignoreTrailingComments": true,
        "ignoreComments": true,
        "ignoreStrings": true,
        "ignoreTemplateLiterals": true
      }
    ],
    "no-trailing-spaces": ["warn", { "skipBlankLines": true, "ignoreComments": true }],
    "no-duplicate-case": "error",
    "no-irregular-whitespace": "warn"
  }
}