KefirJS and WebSockets about kefir HOT 4 CLOSED

Kefir observables generally shouldn't be thought of as objects supporting both read and write operations. Think of the Kefir observable as just representing the read side.

I frequently do things like this:

class WebSocketConnection {
  constructor(socket) {
    this._socket = socket;
    this.stream = Kefir.stream(emitter => {
      socket.on('data', e => emitter.value(e));
      socket.on('end', () => emitter.end());
    });
  }

  write(value) {
    this._socket.write(value);
  }

  close() {
    this._socket.close();
  }
}

const wsc = new WebSocketConnection(...);
wsc.stream
  .filter(value => value.type === 'bar')
  .onValue(value => {
    console.log('got bar event', value);
    console.log('responding');
    wsc.write({type: foo, data: value.data + 1});
  });

Note a small difference between @mAAdhaTTah's code and mine: his closes the socket when no one is listening. Depending on your use-case, that may be what you want. But if you don't always have listeners (generally in a very idiomatic reactive codebase you set up a bunch of listeners at the start that stick around, but if you're just using Kefir here and there in a more classic object-oriented codebase that may not be the case) and still want to write to the connection at any time, then you may not want to automatically close it in that case and instead want an explicit close method like here.

from kefir.

Loosely speaking:

const socket$ = Kefir.stream(emitter => {
  const socket = createSocket();
  socket.on('event', e => emitter.value(e));
  return () => socket.close();
});

from kefir.

I'm going to close this issue, since it's not a bug, but feel free to ask follow-up questions!

from kefir.

I know this is long closed, but I found that the following code also works and I felt it's too cool not to share.

// I imported fromEvents directly from 'kefir'
let myWsStream = fromEvents(websocket, 'message')

from kefir.