Frame.waitForFunction() method
Signature
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 | Type | Description |
---|---|---|
pageFunction | Func | string | the function to evaluate in the frame context. |
options | (Optional) options to configure the polling method and timeout. | |
args | Params | arguments to pass to the |
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';
(async () => {
. 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
);