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waitForFunction(pageFunction, arg[, options])

Returns when the pageFunction returns a truthy value.

ParameterTypeDefaultDescription
pageFunctionfunctionFunction to be evaluated in the page context.
argstring''Optional argument to pass to pageFunction
optionsobjectnull
options.pollingnumber or rafrafIf 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.timeoutnumber30000Maximum time in milliseconds. Pass 0 to disable the timeout. Default is overridden by the setDefaultTimeout option on BrowserContext or Page.

Returns

TypeDescription
Promise< JSHandle>The JSHandle instance associated with the page.

Example

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

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

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

  try {
    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,
    });
    check(ok, { 'waitForFunction successfully resolved': ok.innerHTML() == 'Hello' });
  } finally {
    page.close();
  }
}