text: import React, { Component } from 'react';
  
  class Greeter extends Component {
    onFirstnameChanged = e => {
      this.props.onFirstnameChanged(e.target.value);
    };
  
    render() {
      const { firstName, lastName } = this.props;
  
      return (
        <div>
          Hallo: {firstName || 'Stranger'} {lastName}
          <input value={firstName} onChange={this.onFirstnameChanged} />
        </div>
      );
    }
  }
  
  export default Greeter;
  