Socket-on-event- callback-.md

title	excerpt
Socket.on(event, callback)	Set up callback functions for various events on the WebSocket connection.

Set up callback functions for various events on the WebSocket connection. Multiple handlers can be defined for the same event.

Parameter	Type	Description
event	string	The event name to define a callback for.
callback	function	The function to call when the event happens.

Event name	Description
open	Emitted when the connection is established
message	Emitted when a message is received from the server.
ping	Emitted when a ping is received from the server. The client will automatically send back a pong.
pong	Emitted when a pong is received from the server.
close	Emitted when the connection is closed by the client Socket.close() or when the server sends the close event with code status 1000 (normal closure).
error	Emitted when an error occurs. Non-normal closure errors will be forwarded.

Example

import ws from 'k6/ws';
import { check } from 'k6';

export default function () {
  const url = 'ws://echo.websocket.org';
  const params = { tags: { my_tag: 'hello' } };

  const response = ws.connect(url, params, function (socket) {
    socket.on('open', function open() {
      console.log('connected');
      socket.send(Date.now());

      socket.setInterval(function timeout() {
        socket.ping();
        console.log('Pinging every 1sec (setInterval test)');
      }, 1000);
    });

    socket.on('ping', function () {
      console.log('PING!');
    });

    socket.on('pong', function () {
      console.log('PONG!');
    });

    socket.on('pong', function () {
      // Multiple event handlers on the same event
      console.log('OTHER PONG!');
    });

    socket.on('message', function (message) {
      console.log(`Received message: ${message}`);
    });

    socket.on('close', function () {
      console.log('disconnected');
    });

    socket.on('error', function (e) {
      if (e.error() != 'websocket: close sent') {
        console.log('An unexpected error occured: ', e.error());
      }
    });

    socket.setTimeout(function () {
      console.log('2 seconds passed, closing the socket');
      socket.close();
    }, 2000);
  });

  check(response, { 'status is 101': (r) => r && r.status === 101 });
}