auto reconnect websocket client

wsClientAutoReconnect.ts

import * as WebSocket from 'ws';
import * as EventEmitter from 'events';
// credit to https://github.com/websockets/ws/wiki/Websocket-client-implementation-for-auto-reconnect

class WebSocketClient extends EventEmitter{
  private number = 0;	// Message number
  private autoReconnectInterval = 5 * 1000;	// ms
  private url: string = '';
  private instance: WebSocket | null = null;

  open(url: string) {
    this.url = url;
    this.instance = new WebSocket(this.url);
    this.instance.on('open',()=>{
      this.onopen();
    });
    this.instance.on('message',(data: string, flags: any)=>{
      this.number++;
      this.onmessage(data, flags, this.number);
    });
    this.instance.on('close',(e: any)=>{
      switch (e.code){
        case 1000:	// CLOSE_NORMAL
          console.log("WebSocket: closed");
          break;
        default:	// Abnormal closure
          this.reconnect(e);
          break;
      }
      this.onclose(e);
    });
    this.instance.on('error',(e: any)=>{
      switch (e.code){
        case 'ECONNREFUSED':
          this.reconnect(e);
          break;
        default:
          this.onerror(e);
          break;
      }
    });
  }

  send (data: string, option?: any) {
    if (!this.instance) {
      return console.error('socket instance is not initialized. must call open(url) first');
    }
    if (this.instance.readyState !== 1) {
      return console.error('socket instance is not in ready state', this.instance.readyState);
    }
    try{
      this.instance.send(data, option);
    } catch (e){
      this.instance.emit('error', e);
    }
  }

  reconnect(e: any) {
    console.log(`WebSocketClient: retry in ${this.autoReconnectInterval}ms`,e);
    this.instance && this.instance.removeAllListeners();
    this.instance = null;
    setTimeout(() => {
      console.log(`WebSocketClient: reconnecting... in ${this.autoReconnectInterval}ms`);
      this.open(this.url);
    }, this.autoReconnectInterval);
  }

  onopen() {
    console.log("WebSocketClient: open", arguments);
    this.emit('open');
  }

  onmessage(data: string, flag: any, _number: number) {
    this.emit('message', data, flag);
  }

  onerror(e: any) {
    console.log("WebSocketClient: errpr", arguments);
    this.emit('error', e);
  }

  onclose(e: any) {
    console.log("WebSocketClient: close", arguments);
    this.emit('close', e);
  }
}
export default WebSocketClient;