mirror of
https://github.com/puppeteer/puppeteer
synced 2024-06-14 14:02:48 +00:00
f07ad2c661
This PR updates the docs regarding configuring puppeteer. In addition, some changes have been made to the documentation generator to show default values on the documentation site. Also fixes: https://github.com/puppeteer/puppeteer/pull/9144
70 lines
1.7 KiB
Markdown
70 lines
1.7 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.evaluteHandle` 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
|
|
|
|
| Parameter | Type | Description |
|
|
| ------------ | -------------- | ------------------------------------------ |
|
|
| pageFunction | Func \| string | a function that is run within the page |
|
|
| args | Params | arguments to be passed to the pageFunction |
|
|
|
|
**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();
|
|
```
|