title: How to share state between users in ReactJS
body: <p>I'm building a multiplayer card game mainly in ReactJS and want to share some state between users (players).  I need each user to be able to know when it's their turn to play and see some things about other users like score and current number of cards in hand, etc.  For example, when one player's turn ends, I need the next player's app to recognize it's their turn and provide the applicable options.</p>
  <p>It seems WebSockets or something based on it would be a good option.  I'm still learning React and other pieces so I'm trying to keep the number of technologies down for now.  I'm considering setting up rapid polling (every 200 ms, perhaps), either to an API or maybe checking against a file on the server or database entries.</p>
  <p>Are there especially concerning performance issues or better options to get it working?  I'm also learning about AWS and Docker and intend to host on AWS, if possible.</p>