Enable react/prefer-stateless-function rule

Author: petersendidit

packages/eslint-config-airbnb/rules/react.js

@@ -104,6 +104,9 @@ module.exports = {
     // Require ES6 class declarations over React.createClass
     // https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prefer-es6-class.md
     'react/prefer-es6-class': [2, 'always'],
+    // Require stateless functions when not using lifecycle methods, setState or ref
+    // https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prefer-stateless-function.md
+    'react/prefer-stateless-function': 2,
     // 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': [2, { 'ignore': [], 'customValidators': [] }],

react/README.md

@@ -27,7 +27,7 @@
 
 ## Class vs `React.createClass` vs stateless
 
-  - If you have internal state and/or refs, prefer `class extends React.Component` over `React.createClass` unless you have a very good reason to use mixins. eslint: [`react/prefer-es6-class`](https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prefer-es6-class.md)
+  - If you have internal state and/or refs, prefer `class extends React.Component` over `React.createClass` unless you have a very good reason to use mixins. eslint: [`react/prefer-es6-class`](https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prefer-es6-class.md) [`react/prefer-stateless-function`](https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prefer-stateless-function.md)
 
     ```javascript
     // bad