Javascript 颤振镖：html addEventListener热重新加载问题

如何删除事件

import 'dart:async';
import 'package:universal_html/html.dart';

class HotKey {
   HotKey._();
   static HotKey _instance = HotKey._();
   static HotKey get instance => _instance;

   StreamController<KeyboardEvent> _streamController;
   void _eventListener(KeyboardEvent event) {
      _streamController.add(event);
   }

   void init() {
     _streamController = StreamController.broadcast();
     Function(dynamic event) eve = (event) => _eventListener(event);
     document.addEventListener('keydown', eve, false);
   }

  Stream<KeyboardEvent> get stream => _streamController.stream;
}

void init() {
   _streamController = StreamController.broadcast();
   Function(dynamic event) eve = (event) => _eventListener(event);
   document.removeEventListener('keydown', eve);
  document.addEventListener('keydown', eve, false);
}