reactintro_form_refactored2.jsx

...

import FirstNameField from './FirstNameField';
import LastNameField from './LastNameField';

class SimpleForm extends React.Component { 
  ...

  render() {
    const { firstNameError, firstName, lastName, lastNameError } = this.state;

    return (
      <div style={style.form}>
        <FirstNameField onChange={this.onFirstNameChange}
                        onBlur={this.onFirstNameBlur}
                        error={firstNameError} />

        <LastNameField onChange={this.onLastNameChange}
                        onBlur={this.onLastNameBlur}
                        error={lastNameError} />

        <Greetings firstName={firstName} lastName={lastName} />
      </div>
    );
  }
}