1668d47b2f
See commits for details. Closes #1837, #5880, #7822, #8101, #8821, #9367, #9382, #9378, #4731
96 lines
2.5 KiB
Markdown
96 lines
2.5 KiB
Markdown
---
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sidebar_label: Page.exposeFunction
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---
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# Page.exposeFunction() method
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The method adds a function called `name` on the page's `window` object. When called, the function executes `puppeteerFunction` in node.js and returns a `Promise` which resolves to the return value of `puppeteerFunction`.
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If the puppeteerFunction returns a `Promise`, it will be awaited.
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:::note
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Functions installed via `page.exposeFunction` survive navigations.
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:::note
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#### Signature:
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```typescript
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class Page {
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exposeFunction(
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name: string,
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pptrFunction:
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| Function
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| {
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default: Function;
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}
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): Promise<void>;
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}
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```
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## Parameters
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| Parameter | Type | Description |
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| ------------ | ---------------------------------- | -------------------------------------------------------------- |
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| name | string | Name of the function on the window object |
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| pptrFunction | Function \| { default: Function; } | Callback function which will be called in Puppeteer's context. |
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**Returns:**
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Promise<void>
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## Example 1
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An example of adding an `md5` function into the page:
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```ts
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import puppeteer from 'puppeteer';
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import crypto from 'crypto';
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(async () => {
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const browser = await puppeteer.launch();
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const page = await browser.newPage();
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page.on('console', msg => console.log(msg.text()));
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await page.exposeFunction('md5', text =>
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crypto.createHash('md5').update(text).digest('hex')
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);
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await page.evaluate(async () => {
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// use window.md5 to compute hashes
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const myString = 'PUPPETEER';
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const myHash = await window.md5(myString);
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console.log(`md5 of ${myString} is ${myHash}`);
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});
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await browser.close();
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})();
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```
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## Example 2
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An example of adding a `window.readfile` function into the page:
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```ts
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import puppeteer from 'puppeteer';
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import fs from 'fs';
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(async () => {
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const browser = await puppeteer.launch();
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const page = await browser.newPage();
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page.on('console', msg => console.log(msg.text()));
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await page.exposeFunction('readfile', async filePath => {
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return new Promise((resolve, reject) => {
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fs.readFile(filePath, 'utf8', (err, text) => {
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if (err) reject(err);
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else resolve(text);
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});
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});
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});
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await page.evaluate(async () => {
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// use window.readfile to read contents of a file
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const content = await window.readfile('/etc/hosts');
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console.log(content);
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});
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await browser.close();
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})();
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```
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