fz-react-cli/src/utils/eventStream.js

A CLI tool for build modern web application and libraries

function createEventStream(heartbeat, heartbeatInfo = null) {
  var clientId = 0;
  var clients = {};
  function everyClient(fn) {
    Object.keys(clients).forEach(function(id) {
      fn(clients[id]);
    });
  }
  setInterval(function heartbeatTick() {
    everyClient(function(client) {
      if (heartbeatInfo) {
        client.write(
          'data: ' +
            JSON.stringify({ type: 'heartbeat', info: heartbeatInfo() }) +
            '\n\n'
        );
      } else {
        client.write('data: ' + JSON.stringify({ type: 'heartbeat' }) + '\n\n');
      }
    });
  }, heartbeat).unref();
  return {
    handler: function(req, res) {
      req.socket.setKeepAlive(true);
      res.writeHead(200, {
        'Access-Control-Allow-Origin': '*',
        'Content-Type': 'text/event-stream;charset=utf-8',
        'Cache-Control': 'no-cache, no-transform',
        Connection: 'keep-alive'
      });
      res.write('\n');
      var id = clientId++;
      clients[id] = res;
      req.on('close', function() {
        delete clients[id];
      });
    },
    publish: function(payload) {
      everyClient(function(client) {
        client.write('data: ' + JSON.stringify(payload) + '\n\n');
      });
    }
  };
}
module.exports = createEventStream;