4815676f21
Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
63 lines
2.0 KiB
Markdown
63 lines
2.0 KiB
Markdown
---
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sidebar_label: Frame.waitForFunction
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---
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# Frame.waitForFunction() method
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#### Signature:
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```typescript
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class Frame {
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waitForFunction<
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Params extends unknown[],
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Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
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>(
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pageFunction: Func | string,
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options?: FrameWaitForFunctionOptions,
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...args: Params
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): Promise<HandleFor<Awaited<ReturnType<Func>>>>;
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}
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```
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## Parameters
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| Parameter | Type | Description |
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| ------------ | ------------------------------------------------------------------------- | ----------------------------------------------------------------- |
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| pageFunction | Func \| string | the function to evaluate in the frame context. |
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| options | [FrameWaitForFunctionOptions](./puppeteer.framewaitforfunctionoptions.md) | _(Optional)_ options to configure the polling method and timeout. |
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| args | Params | arguments to pass to the <code>pageFunction</code>. |
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**Returns:**
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Promise<[HandleFor](./puppeteer.handlefor.md)<Awaited<ReturnType<Func>>>>
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the promise which resolve when the `pageFunction` returns a truthy value.
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## Example
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The `waitForFunction` can be used to observe viewport size change:
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```ts
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import puppeteer from 'puppeteer';
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(async () => {
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. const browser = await puppeteer.launch();
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. const page = await browser.newPage();
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. const watchDog = page.mainFrame().waitForFunction('window.innerWidth < 100');
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. page.setViewport({width: 50, height: 50});
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. await watchDog;
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. await browser.close();
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})();
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```
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To pass arguments from Node.js to the predicate of `page.waitForFunction` function:
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```ts
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const selector = '.foo';
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await frame.waitForFunction(
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selector => !!document.querySelector(selector),
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{}, // empty options object
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selector
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);
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```
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