WebSockets
var ws = new WebSocket('ws://host.com/path');
ws.onopen = () => {
  // connection opened
  ws.send('something'); // send a message
};
ws.onmessage = (e) => {
  // a message was received
  console.log(e.data);
};
ws.onerror = (e) => {
  // an error occurred
  console.log(e.message);
};
ws.onclose = (e) => {
  // connection closed
  console.log(e.code, e.reason);
};