Frame.waitForFunction() method

Signature

typescript

class Frame {
  waitForFunction<
    Params extends unknown[],
    Func extends EvaluateFunc<Params> = EvaluateFunc<Params>,
  >(
    pageFunction: Func | string,
    options?: FrameWaitForFunctionOptions,
    ...args: Params
  ): Promise<HandleFor<Awaited<ReturnType<Func>>>>;
}

Parameters

Parameter

</th><th>

Type

</th><th>

Description

</th></tr></thead> <tbody><tr><td>

pageFunction

</td><td>

Func | string

</td><td>

the function to evaluate in the frame context.

</td></tr> <tr><td>

options

</td><td>

FrameWaitForFunctionOptions

</td><td>

(Optional) options to configure the polling method, timeout and signal.

</td></tr> <tr><td>

args

</td><td>

Params

</td><td>

arguments to pass to the pageFunction.

</td></tr> </tbody></table>

Returns:

Promise<HandleFor<Awaited<ReturnType<Func>>>>

the promise which resolve when the pageFunction returns a truthy value.

Example

The waitForFunction can be used to observe viewport size change:

import puppeteer from 'puppeteer';

const browser = await puppeteer.launch();
const page = await browser.newPage();
const watchDog = page.mainFrame().waitForFunction('window.innerWidth < 100');
page.setViewport({width: 50, height: 50});
await watchDog;
await browser.close();

To pass arguments from Node.js to the predicate of page.waitForFunction function:

const selector = '.foo';
await frame.waitForFunction(
  selector => !!document.querySelector(selector),
  {}, // empty options object
  selector,
);