puppeteer/docs/api/puppeteer.frame.waitforfunction.md

---
sidebar_label: Frame.waitForFunction
---
# 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 | Type | Description |
|  --- | --- | --- |
|  pageFunction | Func \| string | the function to evaluate in the frame context. |
|  options | [FrameWaitForFunctionOptions](./puppeteer.framewaitforfunctionoptions.md) | <i>(Optional)</i> options to configure the polling method and timeout. |
|  args | Params | arguments to pass to the <code>pageFunction</code>. |

**Returns:**

Promise&lt;[HandleFor](./puppeteer.handlefor.md)&lt;Awaited&lt;ReturnType&lt;Func&gt;&gt;&gt;&gt;

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

## Remarks


## Example

The `waitForFunction` can be used to observe viewport size change:

```ts
const puppeteer = require('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:

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