Use websockets inside an event emitter

Question

I have a simple class which extends the EventEmitter object from node:events , like this:

export class SimpleService extends EventEmitter {
  constructor() {
    super();
  }

  execute() {
    try {
      const webSocket = new WebSocket('wss://server-socket:1234');

      webSocket.onopen = function () {
        this.emit('data', 'Web socket connection is opened...');
      };
    } catch (error) {
      this.emit('error', error);
    }
  }

The execute method created the WebSocket, and when it is opened, I emit this information. The client is like this:

const simpleService = new SimpleService();

simpleService
  .on('error', (error) => {
    console.log('ERRORRR');
  })
  .on('data', (data) => {
    console.log(data);
  })
  .execute();

but when I run it, it does not show the data emitted from the service, if they are inside webSocket methods.

Answer 1

I just needed to change

webSocket.onopen = function () {
  this.emit('data', 'Web socket connection is opened...');
 };

into

webSocket.on('open',() => {
  this.emit('data', 'Web socket connection is opened...');
 });

What is the reason for this?