puppeteer/new-docs/puppeteer.page.waitforfunction.md

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[Home](./index.md) &gt; [puppeteer](./puppeteer.md) &gt; [Page](./puppeteer.page.md) &gt; [waitForFunction](./puppeteer.page.waitforfunction.md)

## Page.waitForFunction() method

<b>Signature:</b>

```typescript
waitForFunction(pageFunction: Function | string, options?: {
        timeout?: number;
        polling?: string | number;
    }, ...args: SerializableOrJSHandle[]): Promise<JSHandle>;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  pageFunction | Function \| string |  |
|  options | { timeout?: number; polling?: string \| number; } |  |
|  args | [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] |  |

<b>Returns:</b>

Promise&lt;[JSHandle](./puppeteer.jshandle.md)<!-- -->&gt;
chore: commit base new-docs (#5973) This adds the new docs that are generated by API Extractor via TSDoc. They are sparse because we do not yet use TSDoc in the codebase. This is the starting point and from here we can work through all the different classes and improve the documentation. 2020-06-04 14:56:45 +00:00			`<!-- Do not edit this file. It is automatically generated by API Documenter. -->`

			`[Home](./index.md) > [puppeteer](./puppeteer.md) > [Page](./puppeteer.page.md) > [waitForFunction](./puppeteer.page.waitforfunction.md)`

			`## Page.waitForFunction() method`

			`<b>Signature:</b>`

			```typescript
chore: fix ESLint violation and lessen rule strictness (#6081) 2020-06-23 11:55:42 +00:00			`waitForFunction(pageFunction: Function \| string, options?: {`
chore: commit base new-docs (#5973) This adds the new docs that are generated by API Extractor via TSDoc. They are sparse because we do not yet use TSDoc in the codebase. This is the starting point and from here we can work through all the different classes and improve the documentation. 2020-06-04 14:56:45 +00:00			`timeout?: number;`
			`polling?: string \| number;`
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 11:44:08 +00:00			`}, ...args: SerializableOrJSHandle[]): Promise<JSHandle>;`
chore: commit base new-docs (#5973) This adds the new docs that are generated by API Extractor via TSDoc. They are sparse because we do not yet use TSDoc in the codebase. This is the starting point and from here we can work through all the different classes and improve the documentation. 2020-06-04 14:56:45 +00:00			```

			`## Parameters`

			`\| Parameter \| Type \| Description \|`
			`\| --- \| --- \| --- \|`
chore: fix ESLint violation and lessen rule strictness (#6081) 2020-06-23 11:55:42 +00:00			`\| pageFunction \| Function \\| string \| \|`
chore: commit base new-docs (#5973) This adds the new docs that are generated by API Extractor via TSDoc. They are sparse because we do not yet use TSDoc in the codebase. This is the starting point and from here we can work through all the different classes and improve the documentation. 2020-06-04 14:56:45 +00:00			`\| options \| { timeout?: number; polling?: string \\| number; } \| \|`
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 11:44:08 +00:00			`\| args \| [SerializableOrJSHandle](./puppeteer.serializableorjshandle.md)<!-- -->\[\] \| \|`
chore: commit base new-docs (#5973) This adds the new docs that are generated by API Extractor via TSDoc. They are sparse because we do not yet use TSDoc in the codebase. This is the starting point and from here we can work through all the different classes and improve the documentation. 2020-06-04 14:56:45 +00:00
			`<b>Returns:</b>`

			`Promise<[JSHandle](./puppeteer.jshandle.md)<!-- -->>`