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Documentation

waitForFunction(pageFunction, arg[, options])

Open source

waitForFunction(pageFunction, arg[, options])

Returns when the pageFunction returns a truthy value.

Parameter	Type	Default	Description
pageFunction	function		Function to be evaluated in the page context.
arg	string	`''`	Optional argument to pass to `pageFunction`
options	object	`null`
options.polling	number or `raf`	`raf`	If `polling` is `'raf'`, then `pageFunction` is constantly executed in `requestAnimationFrame` callback. If `polling` is a number, then it is treated as an interval in milliseconds at which the function would be executed.
options.timeout	number	`30000`	Maximum time in milliseconds. Pass `0` to disable the timeout. Default is overridden by the `setDefaultTimeout` option on BrowserContext or Page.

Returns

Type	Description
Promise<JSHandle>	The `JSHandle` instance associated with the page.

Example

import { browser } from 'k6/browser';
import { check } from 'https://jslib.k6.io/k6-utils/1.5.0/index.js';

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

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

  try {
    await page.evaluate(() => {
      setTimeout(() => {
        const el = document.createElement('h1');
        el.innerHTML = 'Hello';
        document.body.appendChild(el);
      }, 1000);
    });

    const ok = await page.waitForFunction("document.querySelector('h1')", {
      polling: 'mutation',
      timeout: 2000,
    });
    await check(ok, {
      'waitForFunction successfully resolved': async (ok) =>
          await ok.innerHTML() == 'Hello'
    });
  } finally {
    await page.close();
  }
}