mirror of
https://github.com/puppeteer/puppeteer
synced 2024-06-14 14:02:48 +00:00
93e9acc410
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>
105 lines
1.8 KiB
Markdown
105 lines
1.8 KiB
Markdown
---
|
|
sidebar_label: Page.evaluate
|
|
---
|
|
|
|
# Page.evaluate() method
|
|
|
|
Evaluates a function in the page's context and returns the result.
|
|
|
|
If the function passed to `page.evaluate` returns a Promise, the function will wait for the promise to resolve and return its value.
|
|
|
|
#### Signature:
|
|
|
|
```typescript
|
|
class Page {
|
|
evaluate<
|
|
Params extends unknown[],
|
|
Func extends EvaluateFunc<Params> = EvaluateFunc<Params>,
|
|
>(
|
|
pageFunction: Func | string,
|
|
...args: Params
|
|
): Promise<Awaited<ReturnType<Func>>>;
|
|
}
|
|
```
|
|
|
|
## Parameters
|
|
|
|
<table><thead><tr><th>
|
|
|
|
Parameter
|
|
|
|
</th><th>
|
|
|
|
Type
|
|
|
|
</th><th>
|
|
|
|
Description
|
|
|
|
</th></tr></thead>
|
|
<tbody><tr><td>
|
|
|
|
pageFunction
|
|
|
|
</td><td>
|
|
|
|
Func \| string
|
|
|
|
</td><td>
|
|
|
|
a function that is run within the page
|
|
|
|
</td></tr>
|
|
<tr><td>
|
|
|
|
args
|
|
|
|
</td><td>
|
|
|
|
Params
|
|
|
|
</td><td>
|
|
|
|
arguments to be passed to the pageFunction
|
|
|
|
</td></tr>
|
|
</tbody></table>
|
|
**Returns:**
|
|
|
|
Promise<Awaited<ReturnType<Func>>>
|
|
|
|
the return value of `pageFunction`.
|
|
|
|
## Example 1
|
|
|
|
```ts
|
|
const result = await frame.evaluate(() => {
|
|
return Promise.resolve(8 * 7);
|
|
});
|
|
console.log(result); // prints "56"
|
|
```
|
|
|
|
You can pass a string instead of a function (although functions are recommended as they are easier to debug and use with TypeScript):
|
|
|
|
## Example 2
|
|
|
|
```ts
|
|
const aHandle = await page.evaluate('1 + 2');
|
|
```
|
|
|
|
To get the best TypeScript experience, you should pass in as the generic the type of `pageFunction`:
|
|
|
|
```ts
|
|
const aHandle = await page.evaluate(() => 2);
|
|
```
|
|
|
|
## Example 3
|
|
|
|
[ElementHandle](./puppeteer.elementhandle.md) instances (including [JSHandle](./puppeteer.jshandle.md)s) can be passed as arguments to the `pageFunction`:
|
|
|
|
```ts
|
|
const bodyHandle = await page.$('body');
|
|
const html = await page.evaluate(body => body.innerHTML, bodyHandle);
|
|
await bodyHandle.dispose();
|
|
```
|