docs/api/puppeteer.frame.waitforfunction.md
class Frame {
waitForFunction<
Params extends unknown[],
Func extends EvaluateFunc<Params> = EvaluateFunc<Params>,
>(
pageFunction: Func | string,
options?: FrameWaitForFunctionOptions,
...args: Params
): Promise<HandleFor<Awaited<ReturnType<Func>>>>;
}
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> </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.
Returns:
Promise<HandleFor<Awaited<ReturnType<Func>>>>
the promise which resolve when the pageFunction returns a truthy value.
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,
);