Drupal ESlint settings. Taken from https://www.drupal.org/node/1955232

.eslintignore

core/assets/vendor/**/*
core/modules/locale/tests/locale_test.js
core/vendor/**/*
sites/**/files/**/*
libraries/**/*
sites/**/libraries/**/*
profiles/**/libraries/**/*
**/js_test_files/**/*

.eslintrc

{
  "extends": "eslint:recommended",
  "env": {
    "browser": true
  },
  "globals": {
    "Drupal": true,
    "drupalSettings": true,
    "drupalTranslations": true,
    "domready": true,
    "jQuery": true,
    "_": true,
    "matchMedia": true,
    "Backbone": true,
    "Modernizr": true,
    "CKEDITOR": true
  },
  "rules": {
    // Errors.
    "array-bracket-spacing": [2, "never"],
    "block-scoped-var": 2,
    "brace-style": [2, "stroustrup", {"allowSingleLine": true}],
    "comma-dangle": [2, "never"],
    "comma-spacing": 2,
    "comma-style": [2, "last"],
    "computed-property-spacing": [2, "never"],
    "curly": [2, "all"],
    "eol-last": 2,
    "eqeqeq": [2, "smart"],
    "guard-for-in": 2,
    "indent": [2, 2, {"SwitchCase": 1}],
    "key-spacing": [2, {"beforeColon": false, "afterColon": true}],
    "linebreak-style": [2, "unix"],
    "lines-around-comment": [2, {"beforeBlockComment": true, "afterBlockComment": false}],
    "new-parens": 2,
    "no-array-constructor": 2,
    "no-caller": 2,
    "no-catch-shadow": 2,
    "no-empty-label": 2,
    "no-eval": 2,
    "no-extend-native": 2,
    "no-extra-bind": 2,
    "no-extra-parens": [2, "functions"],
    "no-implied-eval": 2,
    "no-iterator": 2,
    "no-label-var": 2,
    "no-labels": 2,
    "no-lone-blocks": 2,
    "no-loop-func": 2,
    "no-multi-spaces": 2,
    "no-multi-str": 2,
    "no-native-reassign": 2,
    "no-nested-ternary": 2,
    "no-new-func": 2,
    "no-new-object": 2,
    "no-new-wrappers": 2,
    "no-octal-escape": 2,
    "no-process-exit": 2,
    "no-proto": 2,
    "no-return-assign": 2,
    "no-script-url": 2,
    "no-sequences": 2,
    "no-shadow-restricted-names": 2,
    "no-spaced-func": 2,
    "no-trailing-spaces": 2,
    "no-undef-init": 2,
    "no-undefined": 2,
    "no-unused-expressions": 2,
    "no-unused-vars": [2, {"vars": "all", "args": "none"}],
    "no-with": 2,
    "object-curly-spacing": [2, "never"],
    "one-var": [2, "never"],
    "quote-props": [2, "consistent-as-needed"],
    "semi": [2, "always"],
    "semi-spacing": [2, {"before": false, "after": true}],
    "space-after-keywords": [2, "always"],
    "space-before-blocks": [2, "always"],
    "space-before-function-paren": [2, {"anonymous": "always", "named": "never"}],
    "space-in-parens": [2, "never"],
    "space-infix-ops": 2,
    "space-return-throw-case": 2,
    "space-unary-ops": [2, { "words": true, "nonwords": false }],
    "spaced-comment": [2, "always"],
    "strict": 2,
    "yoda": [2, "never"],
    // Warnings.
    "max-nested-callbacks": [1, 3],
    "valid-jsdoc": [1, {
      "prefer": {
        "returns": "return",
        "property": "prop"
      },
      "requireReturn": false
    }]
  }
}