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Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Nikolay Vitkov <nvitkov@chromium.org>
129 lines
2.8 KiB
Markdown
129 lines
2.8 KiB
Markdown
---
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sidebar_label: Page.$$eval
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---
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# Page.$$eval() method
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This method runs `Array.from(document.querySelectorAll(selector))` within the page and passes the result as the first argument to the `pageFunction`.
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#### Signature:
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```typescript
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class Page {
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$$eval<
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Selector extends string,
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Params extends unknown[],
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Func extends EvaluateFuncWith<
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Array<NodeFor<Selector>>,
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Params
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> = EvaluateFuncWith<Array<NodeFor<Selector>>, Params>,
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>(
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selector: Selector,
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pageFunction: Func | string,
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...args: Params
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): Promise<Awaited<ReturnType<Func>>>;
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}
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```
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## Parameters
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<table><thead><tr><th>
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Parameter
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</th><th>
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Type
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</th><th>
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Description
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</th></tr></thead>
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<tbody><tr><td>
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selector
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</td><td>
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Selector
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</td><td>
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the [selector](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors) to query for
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</td></tr>
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<tr><td>
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pageFunction
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</td><td>
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Func \| string
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</td><td>
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the function to be evaluated in the page context. Will be passed the result of `Array.from(document.querySelectorAll(selector))` as its first argument.
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</td></tr>
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<tr><td>
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args
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</td><td>
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Params
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</td><td>
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any additional arguments to pass through to `pageFunction`.
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</td></tr>
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</tbody></table>
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**Returns:**
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Promise<Awaited<ReturnType<Func>>>
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The result of calling `pageFunction`. If it returns an element it is wrapped in an [ElementHandle](./puppeteer.elementhandle.md), else the raw value itself is returned.
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## Remarks
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If `pageFunction` returns a promise `$$eval` will wait for the promise to resolve and then return its value.
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## Example 1
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```ts
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// get the amount of divs on the page
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const divCount = await page.$$eval('div', divs => divs.length);
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// get the text content of all the `.options` elements:
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const options = await page.$$eval('div > span.options', options => {
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return options.map(option => option.textContent);
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});
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```
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If you are using TypeScript, you may have to provide an explicit type to the first argument of the `pageFunction`. By default it is typed as `Element[]`, but you may need to provide a more specific sub-type:
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## Example 2
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```ts
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// if you don't provide HTMLInputElement here, TS will error
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// as `value` is not on `Element`
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await page.$$eval('input', (elements: HTMLInputElement[]) => {
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return elements.map(e => e.value);
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});
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```
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The compiler should be able to infer the return type from the `pageFunction` you provide. If it is unable to, you can use the generic type to tell the compiler what return type you expect from `$$eval`:
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## Example 3
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```ts
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// The compiler can infer the return type in this case, but if it can't
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// or if you want to be more explicit, provide it as the generic type.
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const allInputValues = await page.$$eval<string[]>(
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'input',
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(elements: HTMLInputElement[]) => elements.map(e => e.textContent)
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);
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```
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