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69 lines
2.0 KiB
Markdown
69 lines
2.0 KiB
Markdown
<!-- Do not edit this file. It is automatically generated by API Documenter. -->
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[Home](./index.md) > [puppeteer](./puppeteer.md) > [Page](./puppeteer.page.md) > [evaluate](./puppeteer.page.evaluate.md)
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## Page.evaluate() method
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<b>Signature:</b>
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```typescript
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evaluate<T extends EvaluateFn>(pageFunction: T, ...args: SerializableOrJSHandle[]): Promise<UnwrapPromiseLike<EvaluateFnReturnType<T>>>;
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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 | T | a function that is run within the page |
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| args | [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] | arguments to be passed to the pageFunction |
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<b>Returns:</b>
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Promise<[UnwrapPromiseLike](./puppeteer.unwrappromiselike.md)<!-- --><[EvaluateFnReturnType](./puppeteer.evaluatefnreturntype.md)<!-- --><T>>>
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the return value of `pageFunction`<!-- -->.
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## Remarks
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Evaluates a function in the page's context and returns the result.
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If the function passed to `page.evaluteHandle` returns a Promise, the function will wait for the promise to resolve and return its value.
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## Example 1
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```js
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const result = await frame.evaluate(() => {
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return Promise.resolve(8 * 7);
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});
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console.log(result); // prints "56"
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```
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You can pass a string instead of a function (although functions are recommended as they are easier to debug and use with TypeScript):
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## Example 2
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```
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const aHandle = await page.evaluate('1 + 2');
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```
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To get the best TypeScript experience, you should pass in as the generic the type of `pageFunction`<!-- -->:
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```
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const aHandle = await page.evaluate<() => number>(() => 2);
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```
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## Example 3
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[ElementHandle](./puppeteer.elementhandle.md) instances (including [JSHandle](./puppeteer.jshandle.md)<!-- -->s) can be passed as arguments to the `pageFunction`<!-- -->:
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```
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const bodyHandle = await page.$('body');
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const html = await page.evaluate(body => body.innerHTML, bodyHandle);
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await bodyHandle.dispose();
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```
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