puppeteer/new-docs/puppeteer.elementhandle._eval.md
Jack Franklin 46fc6ca41a
feat(types): improve typing of .evaluate() (#6096)
* feat(types): improve typing of `.evaluate()`

This is the start of the work to take the types from the
`@types/puppeteer` repository and port them into our repo so we can ship
our built-in types out the box.

This change types the `evaluate` function properly. It takes a generic
type which is the type of the function you're passing, and the arguments
and the return that you get back from the `evaluate` call are typed
correctly.
2020-06-25 13:38:01 +01:00

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<!-- Do not edit this file. It is automatically generated by API Documenter. -->
[Home](./index.md) &gt; [puppeteer](./puppeteer.md) &gt; [ElementHandle](./puppeteer.elementhandle.md) &gt; [$eval](./puppeteer.elementhandle._eval.md)
## ElementHandle.$eval() method
This method runs `document.querySelector` within the element and passes it as the first argument to `pageFunction`<!-- -->. If there's no element matching `selector`<!-- -->, the method throws an error.
If `pageFunction` returns a Promise, then `frame.$eval` would wait for the promise to resolve and return its value.
<b>Signature:</b>
```typescript
$eval<ReturnType extends any>(selector: string, pageFunction: EvaluateFn | string, ...args: SerializableOrJSHandle[]): Promise<ReturnType>;
```
## Parameters
| Parameter | Type | Description |
| --- | --- | --- |
| selector | string | |
| pageFunction | [EvaluateFn](./puppeteer.evaluatefn.md) \| string | |
| args | [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] | |
<b>Returns:</b>
Promise&lt;ReturnType&gt;
## Example
```js
const tweetHandle = await page.$('.tweet');
expect(await tweetHandle.$eval('.like', node => node.innerText)).toBe('100');
expect(await tweetHandle.$eval('.retweets', node => node.innerText)).toBe('10');
```