ddbb43cd09
Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
70 lines
1.7 KiB
Markdown
70 lines
1.7 KiB
Markdown
---
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sidebar_label: Page.evaluate
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---
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# Page.evaluate() method
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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.evaluate` returns a Promise, the function will wait for the promise to resolve and return its value.
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#### Signature:
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```typescript
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class Page {
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evaluate<
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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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...args: Params
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): Promise<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 | a function that is run within the page |
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| args | Params | arguments to be passed to the pageFunction |
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**Returns:**
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Promise<Awaited<ReturnType<Func>>>
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the return value of `pageFunction`.
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## Example 1
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```ts
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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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```ts
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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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```ts
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const aHandle = await page.evaluate(() => 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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```ts
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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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