on(event, handler)

Registers a handler to be called whenever the specified event occurs.

Parameter	Type	Default	Description
event	string	`''`	Event to attach the handler to. Currently, only the `'console'` event is supported.
handler	function	`null`	A function to be called every time the specified event is emitted.

Caution: When using the page.on method, the page has to be explicitly closed for the iteration to be able to finish.

Events

Event	Description
`console`	Emitted every time the console API methods are called from within the page JavaScript context. The arguments passed into the handler are defined by the `ConsoleMessage` class.

Example

import { browser } from 'k6/x/browser';
import { check } from 'k6';

export const options = {
  scenarios: {
    ui: {
      executor: 'shared-iterations',
      options: {
        browser: {
          type: 'chromium',
        },
      },
    },
  },
  thresholds: {
    checks: ['rate==1.0'],
  },
};

export default async function () {
  const page = browser.newPage();

  try {
    await page.goto('https://test.k6.io/');

    page.on('console', (msg) => {
      check(msg, {
        assertConsoleMessageType: (msg) => msg.type() == 'log',
        assertConsoleMessageText: (msg) => msg.text() == 'this is a console.log message 42',
        assertConsoleMessageArgs0: (msg) => msg.args()[0].jsonValue() == 'this is a console.log message',
        assertConsoleMessageArgs1: (msg) => msg.args()[1].jsonValue() == 42,
      });
    });

    page.evaluate(() => console.log('this is a console.log message', 42));
  } finally {
    page.close(); // required so iteration can end
  }
}