59 lines
1.7 KiB
Markdown
59 lines
1.7 KiB
Markdown
<!-- Do not edit this file. It is automatically generated by API Documenter. -->
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[Home](./index.md) > [puppeteer](./puppeteer.md) > [Frame](./puppeteer.frame.md) > [waitForFunction](./puppeteer.frame.waitforfunction.md)
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## Frame.waitForFunction() method
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<b>Signature:</b>
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```typescript
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waitForFunction(pageFunction: Function | string, options?: FrameWaitForFunctionOptions, ...args: SerializableOrJSHandle[]): Promise<JSHandle>;
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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 | Function \| string | the function to evaluate in the frame context. |
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| options | [FrameWaitForFunctionOptions](./puppeteer.framewaitforfunctionoptions.md) | options to configure the polling method and timeout. |
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| args | [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] | arguments to pass to the <code>pageFunction</code>. |
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<b>Returns:</b>
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Promise<[JSHandle](./puppeteer.jshandle.md)<!-- -->>
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the promise which resolve when the `pageFunction` returns a truthy value.
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## Remarks
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## Example
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The `waitForFunction` can be used to observe viewport size change:
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```js
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const puppeteer = require('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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```js
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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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