How to set focus on an input field after rendering?

What's the react way of setting focus on a particular text field after the component is rendered?

Documentation seems to suggest using refs, e.g:

Set ref="nameInput" on my input field in the render function, and then call:


But where should I call this? I've tried a few places but I cannot get it to work.

<input type="text" autoFocus />

always try the simple and basic solution first, works for me.