.eslintrc.json

{
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module",
    "ecmaFeatures": {
      "experimentalObjectRestSpread": true
    }
  },
  "extends": "eslint:recommended",

  "rules": {
    // 0 = allowed, 1 = warning, 2 = error.

    "no-multiple-empty-lines": [2, {"max": 2}],
    "max-len": ["error", {
      "code": 136,
      "tabWidth": 4,
      "ignoreComments": true,
      "ignoreTrailingComments": true,
      "ignoreStrings": true,
      "ignoreUrls": true,
      "ignoreTemplateLiterals": true,
      "ignoreRegExpLiterals": true
    }],

    // Javascript
    "no-unused-vars": 0, /* Allow unused variables. Good for leaving unused function parameters visible */
    "no-extra-boolean-cast": 0, /* Allow for unnecessary '!!value'. FIXME: let's try tighten this  */
    "no-redeclare": 0, /* Allow for variables to be redefined. There are scenarios where this allows for cleaner code. */

    "block-scoped-var": 2, // Enforces vars defined aren't used outwith their defined block.
    "dot-notation": 2, // Enforces accessing object properites via dot notation.
    "no-alert": 1, // Throws warning use of alert, confirm and prompt dialogues.
    "no-extend-native": 2, // Prevents extending native JS objects.
    "no-floating-decimal": 2, // Prevents using decimal place with prefixing / suffixing with numeric e.g. '.5'
    "no-lone-blocks": 2, // Prevents use of an empty block e.g. {}

    "no-self-compare": 2, // Prevents comparing vars to themselves
    "yoda": 2, // Prevents reversed comparison.
    "no-undef-init": 2, // Prevents settings a var to undefined.
    "prefer-const": 2,

    // Node JS
    "global-require": 1, // Enforces all require statements to be made at the top of the file. TODO: Enfore this.
    "handle-callback-err": 0, // TODO: We want to enforce this, but it's quite a large change to codebase. Integrate this once we've solidified loading an error page.
    "no-sync": 2, // warns whever a synchronous methods is used. TODO: @andi, does the readFileSync in app.js need to be synchronous?

    // Stylistic
    "comma-dangle": ["error", "always-multiline"],
    "consistent-this": 2, // Enforces consisten naming of "this" object assignment to be named "that".
    "func-call-spacing": 2, // Enforces function calls to have no spacing e.g. doSomething(param).
    "indent": ["error", 4, { "SwitchCase": 1 }], // Enforces project to use 4 spaces as a tab, including case statements
    "no-var": 2,
    "semi": [2, "always"],
    "brace-style": ["error", "1tbs", {"allowSingleLine": true}], // Enforces same-line "} else ..." statements.
    "eol-last": ["error", "always"],
    "object-curly-spacing": ["error", "always"]
  },

  /* Sets which variables are available & globally accessible */
  "env": {
    "node": true,
    "mocha": true
  }
}