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

1.3 KiB

Home > puppeteer > ElementHandle > $eval

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.

Signature:

$eval<ReturnType extends any>(selector: string, pageFunction: EvaluateFn | string, ...args: SerializableOrJSHandle[]): Promise<ReturnType>;

Parameters

Parameter Type Description
selector string
pageFunction EvaluateFn | string
args SerializableOrJSHandle[]

Returns:

Promise<ReturnType>

Example

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');