Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

Documentation

evaluate(pageFunction[, arg])

Open source

evaluate(pageFunction[, arg])

Returns the value of the pageFunction invocation.

Parameter	Type	Defaults	Description
pageFunction	function or string		Function to be evaluated in the page context. This can also be a string.
arg	string	`''`	Optional argument to pass to `pageFunction`

Returns

Type	Description
`Promise<any>`	The value of the `pageFunction` invocation.

Example

JavaScript
import { browser } from 'k6/browser';
import { check } from 'k6/http';

export const options = {
  scenarios: {
    browser: {
      executor: 'shared-iterations',
      options: {
        browser: {
          type: 'chromium',
        },
      },
    },
  },
};

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

  await page.goto('https://test.k6.io/browser.php');
  const dimensions = await page.evaluate(() => {
    const obj = {
      width: document.documentElement.clientWidth,
      height: document.documentElement.clientHeight,
      deviceScaleFactor: window.devicePixelRatio,
    };
    return obj;
  });

  check(dimensions, {
    width: (d) => d.width === 1280,
    height: (d) => d.height === 720,
    scale: (d) => d.deviceScaleFactor === 1,
  });
}