.eslintrc.json

{
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module",
    "ecmaFeatures": {
      "jsx": true
    }
  },
  "env": {
    "es6": true,
    "browser": true,
    "node": true
  },
  "rules": {
    // prohibits bitwise operators (&, |, ^, etc.)
    "no-bitwise": 2,
    // require {} for every new block or scope
    "curly": [1, "all"],
    // require using === or !== always
    "eqeqeq": [2, "always"],
    // require calling Object.prototype.hasOwnProperty.call(obj, key) in for in loops
    "guard-for-in": 1,
    // disallow calling obj.hasOwnProperty. Use Object.prototype.hasOwnProperty.call instead
    "no-prototype-builtins": 1,
    // required parentheses around imediately invoked functions
    "wrap-iife": [2, "inside"],
    // enforce comments' first word to be lowercase
    "no-empty": [1, { "allowEmptyCatch": true }],
    // prohibits the use of ++ and --
    "no-plusplus": 1,
    // enforce double quotations or backticks whenever needed
    "quotes": [2, "double"],
    // prevent the use of global variables unless declared
    "no-undef": 2,
    // force using strict at the beginning of the file (global param)
    "strict": [2, "global"],
    // enforce a maximum of 4 parameter per function
    "max-params": [1, 4],
    // enforce a maximum depth of 4 per function
    "max-depth": [1, 4],
    // enforce a maximum of 15 statements per function
    "max-statements": [1, 15],
    // enforce a maximum of 50 lines per functions
    "max-lines-per-function": [1, 50],
    // enforce a max length of 100 for code and 70 for commments
    "max-len": [1, {"code": 100, "comments": 80, "ignoreUrls": true }],
    // limit the max nested callbacks to 2
    "max-nested-callbacks": [1, 2],
    // require using let or const
    "no-var": 2,
    // require using a whitespace after a comment
    "spaced-comment": [2, "always"]
  }
}