A sample Eslint configuration

.eslintrc

{
  "parser": "babel-eslint",
  "parserOptions": {
    "ecmaVersion": 7,
    "sourceType": "module",
    "ecmaFeatures": {
      "jsx": true,
      "modules": true,
      "experimentalObjectRestSpread": true
    }
  },
  "env": {
    "browser": true,
    "node": true,
    "es6": true,
  },
  "globals" : {
    "__CASINO_ENV__": true,
    "__BUILD_COMMIT_ID__": true
  },
  "plugins": [
    "react"
  ],
  "extends": ["eslint:recommended", "plugin:react/recommended"],
  "rules": {
    "react/prop-types": 1,
    "react/jsx-uses-react": 2,
    "react/jsx-uses-vars": 2,
    "react/react-in-jsx-scope": 2,

    "array-bracket-spacing": [2, "never"],
    "block-scoped-var": [0],
    "brace-style": [1, "stroustrup", {"allowSingleLine": true}],
    "camelcase": [0],
    "comma-dangle": [2, "always-multiline"], // important for cleaner diffs and easier merge conflict resolution
    "comma-spacing": [2],
    "comma-style": [2, "last"],
    "complexity": [0, 11],
    "computed-property-spacing": [2, "never"],
    "consistent-return": [1],
    "consistent-this": [0, "that"],
    "curly": [2, "multi-line"],
    "default-case": [0],
    "dot-notation": [2, {"allowKeywords": true}],
    "eol-last": [1],
    "eqeqeq": [1],
    "func-names": [0],
    "func-style": [0, "declaration"],
    "generator-star-spacing": [2, "after"],
    "guard-for-in": [0],
    "handle-callback-err": [0],
    "key-spacing": [2, {"beforeColon": false, "afterColon": true}],
    "keyword-spacing": [2],
    "quotes": [2, "single", "avoid-escape"],
    "max-depth": [0, 4],
    "max-len": [1, {
      "code": 100,
      "ignoreComments": true,
      "ignorePattern": "^\\s*import\\s.+\\sfrom\\s.+"
    }],
    "max-nested-callbacks": [0, 2],
    "max-params": [0, 3],
    "max-statements": [0, 10],
    "new-parens": [2],
    "new-cap": [0],
    "newline-after-var": [0],
    "no-alert": [2],
    "no-array-constructor": [2],
    "no-bitwise": [0],
    "no-caller": [2],
    "no-case-declarations": 0,
    "no-catch-shadow": [2],
    "no-cond-assign": [2],
    "no-console": [1],
    "no-const-assign": [2],
    "no-constant-condition": [1],
    "no-continue": [2],
    "no-control-regex": [2],
    "no-debugger": [1],
    "no-delete-var": [2],
    "no-div-regex": [0],
    "no-dupe-args": [2],
    "no-dupe-keys": [2],
    "no-duplicate-case": [2],
    "no-else-return": [0],
    "no-empty": [2],
    "no-empty-character-class": [2],
    "no-eq-null": [0],
    "no-eval": [2],
    "no-ex-assign": [2],
    "no-extend-native": [1],
    "no-extra-bind": [2],
    "no-extra-boolean-cast": [2],
    "no-extra-semi": [1],
    "no-fallthrough": [2],
    "no-floating-decimal": [2],
    "no-func-assign": [2],
    "no-implied-eval": [2],
    "no-inline-comments": [0],
    "no-inner-declarations": [2, "functions"],
    "no-invalid-regexp": [2],
    "no-irregular-whitespace": [2],
    "no-iterator": [2],
    "no-label-var": [2],
    "no-labels": [2],
    "no-lone-blocks": [2],
    "no-lonely-if": [2],
    "no-loop-func": [0],
    "no-mixed-requires": [0, false],
    "no-mixed-spaces-and-tabs": [2, false],
    "no-multi-spaces": [2],
    "no-multi-str": [2],
    "no-multiple-empty-lines": [2, {"max": 2}],
    "no-native-reassign": [1],
    "no-negated-in-lhs": [2],
    "no-nested-ternary": [1],
    "no-new": [2],
    "no-new-func": [2],
    "no-new-object": [2],
    "no-new-require": [0],
    "no-new-wrappers": [2],
    "no-obj-calls": [2],
    "no-octal": [2],
    "no-octal-escape": [2],
    "no-param-reassign": [2],
    "no-path-concat": [0],
    "no-plusplus": [0],
    "no-process-env": [0],
    "no-process-exit": [2],
    "no-proto": [2],
    "no-redeclare": [2],
    "no-regex-spaces": [2],
    "no-reserved-keys": [0],
    "no-restricted-modules": [0],
    "no-return-assign": [2],
    "no-script-url": [2],
    "no-self-compare": [0],
    "no-sequences": [2],
    "no-shadow": [2],
    "no-shadow-restricted-names": [2],
    "no-spaced-func": [2],
    "no-sparse-arrays": [2],
    "no-sync": [0],
    "no-ternary": [0],
    "no-throw-literal": [2],
    "no-trailing-spaces": [2],
    "no-undef": [2],
    "no-undef-init": [2],
    "no-undefined": [0],
    "no-underscore-dangle": [0],
    "no-unreachable": [2],
    "no-unused-expressions": [2],
    "no-unused-vars": [1, {"vars": "all", "args": "after-used"}],
    "no-use-before-define": [2],
    "no-void": [0],
    "no-warning-comments": [0, {"terms": ["todo", "fixme", "xxx"], "location": "start"}],
    "no-with": [2],
    "no-extra-parens": [0],
    "object-curly-spacing": [2, "never"],
    "one-var": [0],
    "operator-assignment": [0, "always"],
    "operator-linebreak": [2, "after"],
    "padded-blocks": [0],
    "quote-props": [0],
    "radix": [0],
    "semi": [2],
    "semi-spacing": [2, {"before": false, "after": true}],
    "sort-vars": [0],
    "space-before-function-paren": [2, {"anonymous": "never", "named": "never"}],
    "space-before-blocks": [2, "always"],
    "space-in-parens": [2, "never"],
    "space-infix-ops": [2],
    "space-unary-ops": [2, {"words": true, "nonwords": false}],
    "spaced-line-comment": [0, "always"],
    "strict": [2, "never"],
    "use-isnan": [2],
    "valid-jsdoc": [0],
    "valid-typeof": [2],
    "vars-on-top": [0],
    "wrap-iife": [2],
    "wrap-regex": [2],
    "yoda": [2, "never", {"exceptRange": true}]
  },
}