WebSocket

Creates a WebSocket instance for connection to a remote host.

The following events can close the connection:

remote host close event.
WebSocket.close().
k6 VU interruption based on test configuration or CLI commands.

Parameter	Type	Description
url	string	The URL to which to connect (e.g. “ws://localhost:10000”).
protocols	array	Not yet implemented, reserved for the future use.
params	object	Params object containing additional request parameters.

Returns

Type	Description
WebSocket	An instance of WebSocket object.

Ready-state constants

Compare an instance’s readyState with these constants to check the connection state:

Constant	Value	Description
`WebSocket.CONNECTING`	`0`	The connection is not yet open.
`WebSocket.OPEN`	`1`	The connection is open and ready to communicate.
`WebSocket.CLOSING`	`2`	The connection is closing.
`WebSocket.CLOSED`	`3`	The connection is closed or could not be opened.

The constants are read-only and also available on each instance, for example, ws.OPEN.

Example

A k6 script that initiates a WebSocket connection.

import { WebSocket } from 'k6/websockets';

export default function () {
  const ws = new WebSocket('wss://quickpizza.grafana.com/ws');

  ws.onopen = () => {
    console.log(ws.readyState === WebSocket.OPEN); // true
    console.log(ws.OPEN === WebSocket.OPEN); // true
    ws.close();
  };

  ws.onclose = () => {
    console.log(ws.readyState === WebSocket.CLOSED); // true
  };
}