.eslintrc

{
  "extends": "airbnb",
  "globals": {
    "expect": true
  },
  "env": {
    "browser": true,
    "node": true,
    "mocha": true
  },
  "rules": {
    // Can be automatically transformed everywhere with `eslint --fix`
    "space-before-function-paren": [2, "never"],

    // in contrast to the old lint configuration, enforce the absence of dangling commas
    "comma-dangle": [2, "never"],

    // allow unnamed anonymous functions
    "func-names": 0,

    // the airbnb toolchain presupposes concatenation and prepending "use strict"
    "strict": 0,

    // deactivate enforced indentation, activate at own peril
    "indent": [0, 2, {"SwitchCase": 1}],

    // allows for placeholder/unused variables that look like: _, __, ___
    "no-unused-vars": [2, { "vars": "local", "varsIgnorePattern": "^_{1,3}$", "args": "after-used" }],

    // allows us to sort functions and classes in a logical order, rather than the inverse inclusion order
    "no-use-before-define": 1,

    // allows to assign to argument properties, but not to arguments
    "no-param-reassign": [2, {"props": false}],

    // allow function values, because some objects don't have methods, they are a collection of functions
    "object-shorthand": 0,

    // would require fat-arrow function definitions even if there is no result -> e.g. in tests `it`
    "prefer-arrow-callback": 0,

    // deactivate, because we want to allow for () => { return {}; } in favour of () => ({})
    "arrow-body-style": 0,

    // for a simple string + value, some of us prefer non-template strings. So enforce on a project-by-project basis
    "prefer-template": 0,

    // Go for a max-len, but set the default higher. Teams may switch the default at their own peril
    "max-len": [2, 120],

    // Enforces single parenthesis around arrow-function parameter lists, independent of parameter count
    "arrow-parens": [2, "always"],

    // Enforce stateless React Components to be written as a pure function
    "react/prefer-stateless-function": "off",

    // Prevent missing props validation in a React component definition
    // https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prop-types.md
    "react/prop-types": ["error", { "ignore": ["key"], "customValidators": [] }],

    "react/jsx-filename-extension": [1, { "extensions": [".js", ".jsx"] }],

    "import/no-extraneous-dependencies": ["error", { "devDependencies": true }],

    "no-unused-expressions": 0
  }
}