Comunicacao de Componentes React

callback-refs.jsx

class ParentComponent extends React.Component
{
  render() {
    return (
      <input type="text" ref={(field) => this.editText = field} />
    )
  }
  componentDidMount() {
    if (this.editText !== null) {
      this.editText.focus()
    }
  }
}

string-refs.jsx

class ParentComponent extends React.Component
{
  render() {
    return (
      <input type="text" ref="editText"/>
    )
  }
  componentDidMount() {
    this.refs.editText.focus()
  }
}