puppeteer/new-docs/puppeteer.page.waitfor.md
Jack Franklin 8370ec88ae
feat(types): add (and fix) evaluateHandle types (#6130)
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'));
```
2020-07-01 12:44:08 +01:00

971 B

Home > puppeteer > Page > waitFor

Page.waitFor() method

Signature:

waitFor(selectorOrFunctionOrTimeout: string | number | Function, options?: {
        visible?: boolean;
        hidden?: boolean;
        timeout?: number;
        polling?: string | number;
    }, ...args: SerializableOrJSHandle[]): Promise<JSHandle>;

Parameters

Parameter Type Description
selectorOrFunctionOrTimeout string | number | Function
options { visible?: boolean; hidden?: boolean; timeout?: number; polling?: string | number; }
args SerializableOrJSHandle[]

Returns:

Promise<JSHandle>