render() {
  return (
    <div>
      <br />
      <input
        type="text"
        value={this.state.message}
        onChange={e => this.setState({ message: e.target.value })}
      />

      <button onClick={this.sendMessage}>Send</button>

      <div>
        {this.state.messages.map((message, index) => (
          <span style={{display: 'block'}} key={index}> {message} </span>
        ))}
      </div>
    </div>
  );
}