How to access EventSource (SSE) API from dart

event_source.dart

import 'dart:html';

class EventSourceModel {
  static const kEndPoint = 'https://myfirebaseendpoint.com';
  EventSource es;
  
  final StreamController<UserMatch> _controller = StreamController<UserMatch>();
  Stream<UserMatch> get stream => _controller.stream;
  
  EventSourceModel() {
    es = EventSource(kEndPoint);
    
    es.onError.listen(_onError);
    es.addEventListener('put', _onPut);
    es.addEventListener('patch', _onPatch);
    es.addEventListener('auth_revoked', _onAuthRevoked);
  }
  
  // replace all of the data at that location in its cache with the data given in the message
  // e.g. new match(es)
  void _onPut(Event e) {
    MessageEvent me = e as MessageEvent;
    Map<String, dynamic> json = jsonDecode(me.data.toString());

    if (json['path'] == '/') {
      Map<String, dynamic> matches = json['data'];

      for (String matchConvoID in matches.keys) {
        Map<String, dynamic> matchObject = matches[matchConvoID];
        _controller.add(_parseMatch(matchConvoID, matchObject));
      }
    } else {
      String matchConvoID = json['path'].toString().substring(1);
      Map<String, dynamic> matchObject = json['data'];
      _controller.add(_parseMatch(matchConvoID, matchObject));
    }
  }
  
  void _onError(Event e) {
    _controller.close();
  }
}

// references:
// https://developer.mozilla.org/en-US/docs/Web/API/EventSource
// https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events