Miscellaneous Frontend Best Practices

Import & Module

JS file and folder name may only contain lowercase alphanumeric characters and hyphen.
Separate your imports into 2 sections: 3rd party libraries and our own code.
If a module contain many things, import exactly those things that you require, not the whole module. i.e. import { findDOMNode, unmountComponentAtNode } from 'react-dom'; is good, import ReactDOM from 'react-dom'; is less nice.

Test module will live at the exact same path as the module it wishes to test. For example, test/components/common/article-footer.js will contain test for src/js/components/common/article-footer.js.
When you need factory, use one or create one using rosie. See here for example.
Some components need required props in order to work. To test such component with should.renderable() (which doesn't pass down any prop), use defaultProps. See example in here.

Wrap your markup in () before returning it and start markup on a separate line, make it easier to read. e.g.

return (
  <p>some text</p>
);

Use arrow functions when the function still look good defined inline and/or it need to use this from outside scope. Callback prop to children is thus a very good usecase for arrow function.