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This change started as a small change to pull types from DefinitelyTyped over to
Puppeteer for the `evaluateHandle` function but instead ended up also fixing
what looks to be a long standing issue with our existing documentation.
`evaluateHandle` can in fact return an `ElementHandle` rather than a `JSHandle`.
Note that `ElementHandle` extends `JSHandle` so whilst the docs are technically
correct (all ElementHandles are JSHandles) it's confusing because JSHandles
don't have methods like `click` on them, but ElementHandles do.
if you return something that is an HTML element:
```
const button = page.evaluateHandle(() => document.querySelector('button'));
// this is an ElementHandle, not a JSHandle
```
Therefore I've updated the original docs and added a large explanation to the
TSDoc for `page.evaluateHandle`.
In TypeScript land we'll assume the function will return a `JSHandle` but you
can tell TS otherwise via the generic argument, which can only be `JSHandle`
(the default) or `ElementHandle`:
```
const button = page.evaluateHandle<ElementHandle>(() => document.querySelector('button'));
```
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1.3 KiB
Home > puppeteer > WebWorker > evaluateHandle
WebWorker.evaluateHandle() method
The only difference between worker.evaluate and worker.evaluateHandle is that worker.evaluateHandle returns in-page object (JSHandle). If the function passed to the worker.evaluateHandle returns a [Promise], then worker.evaluateHandle would wait for the promise to resolve and return its value. Shortcut for await worker.executionContext()).evaluateHandle(pageFunction, ...args)
Signature:
evaluateHandle<HandlerType extends JSHandle = JSHandle>(pageFunction: EvaluateHandleFn, ...args: SerializableOrJSHandle[]): Promise<JSHandle>;
Parameters
| Parameter | Type | Description |
|---|---|---|
| pageFunction | EvaluateHandleFn | Function to be evaluated in the page context. |
| args | SerializableOrJSHandle[] | Arguments to pass to pageFunction. |
Returns:
Promise<JSHandle>
Promise which resolves to the return value of pageFunction.