3aee641c3d
🤖 I have created a release *beep* *boop* --- ## [18.1.0](https://github.com/puppeteer/puppeteer/compare/v18.0.5...v18.1.0) (2022-10-05) ### Features * **chromium:** roll to Chromium 107.0.5296.0 (r1045629) ([#9039](https://github.com/puppeteer/puppeteer/issues/9039)) ([022fbde](022fbde85e)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
88 lines
2.6 KiB
Markdown
88 lines
2.6 KiB
Markdown
---
|
|
sidebar_label: Page.waitForFunction
|
|
---
|
|
|
|
# Page.waitForFunction() method
|
|
|
|
Waits for a function to finish evaluating in the page's context.
|
|
|
|
**Signature:**
|
|
|
|
```typescript
|
|
class Page {
|
|
waitForFunction<
|
|
Params extends unknown[],
|
|
Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
|
|
>(
|
|
pageFunction: Func | string,
|
|
options?: FrameWaitForFunctionOptions,
|
|
...args: Params
|
|
): Promise<HandleFor<Awaited<ReturnType<Func>>>>;
|
|
}
|
|
```
|
|
|
|
## Parameters
|
|
|
|
| Parameter | Type | Description |
|
|
| ------------ | ------------------------------------------------------------------------- | ----------------------------------------------------------- |
|
|
| pageFunction | Func \| string | Function to be evaluated in browser context |
|
|
| options | [FrameWaitForFunctionOptions](./puppeteer.framewaitforfunctionoptions.md) | <i>(Optional)</i> Options for configuring waiting behavior. |
|
|
| args | Params | |
|
|
|
|
**Returns:**
|
|
|
|
Promise<[HandleFor](./puppeteer.handlefor.md)<Awaited<ReturnType<Func>>>>
|
|
|
|
## Example 1
|
|
|
|
The [Page.waitForFunction()](./puppeteer.page.waitforfunction.md) can be used to observe viewport size change:
|
|
|
|
```ts
|
|
const puppeteer = require('puppeteer');
|
|
(async () => {
|
|
const browser = await puppeteer.launch();
|
|
const page = await browser.newPage();
|
|
const watchDog = page.waitForFunction('window.innerWidth < 100');
|
|
await page.setViewport({width: 50, height: 50});
|
|
await watchDog;
|
|
await browser.close();
|
|
})();
|
|
```
|
|
|
|
## Example 2
|
|
|
|
To pass arguments from node.js to the predicate of [Page.waitForFunction()](./puppeteer.page.waitforfunction.md) function:
|
|
|
|
```ts
|
|
const selector = '.foo';
|
|
await page.waitForFunction(
|
|
selector => !!document.querySelector(selector),
|
|
{},
|
|
selector
|
|
);
|
|
```
|
|
|
|
## Example 3
|
|
|
|
The predicate of [Page.waitForFunction()](./puppeteer.page.waitforfunction.md) can be asynchronous too:
|
|
|
|
```ts
|
|
const username = 'github-username';
|
|
await page.waitForFunction(
|
|
async username => {
|
|
const githubResponse = await fetch(
|
|
`https://api.github.com/users/${username}`
|
|
);
|
|
const githubUser = await githubResponse.json();
|
|
// show the avatar
|
|
const img = document.createElement('img');
|
|
img.src = githubUser.avatar_url;
|
|
// wait 3 seconds
|
|
await new Promise((resolve, reject) => setTimeout(resolve, 3000));
|
|
img.remove();
|
|
},
|
|
{},
|
|
username
|
|
);
|
|
```
|