119 lines
4.7 KiB
Markdown
119 lines
4.7 KiB
Markdown
# Puppeteer [](https://travis-ci.com/GoogleChrome/puppeteer)
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Puppeteer is a Node library which provides a high-level API to control Chromium over the [DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/). Puppeteer is inspired by [PhantomJS](http://phantomjs.org/). Check our [FAQ](#faq) to learn more.
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## Use Cases
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* Up-to-date testing environment that supports the latest Javascript features.
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* Crawl your site to generate pre-rendered content for your SPA.
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* Scrape content from websites.
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## Installation
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Get the source:
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```
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git clone https://github.com/GoogleChrome/puppeteer
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cd puppeteer
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```
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Install the dependencies:
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```
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yarn
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```
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or use `npm`:
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```
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npm install
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```
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> Note: Puppeteer bundles Chromium (~70Mb) which it is guaranteed to work with. However, you're free to point Puppeteer to any Chromium executable ([example](https://github.com/GoogleChrome/puppeteer/blob/master/examples/custom-chromium-revision.js))
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## Getting Started
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The following script navigates to https://example.com and saves a screenshot to *example.png*:
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```javascript
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const Browser = require('Puppeteer').Browser;
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const browser = new Browser();
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browser.newPage().then(async page => {
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await page.navigate('https://example.com');
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await page.screenshot({path: 'example.png'});
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browser.close();
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});
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```
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A few notes:
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1. By default, Puppeteer runs a bundled Chromium browser. However, you can point Puppeteer to a different executable ([example](https://github.com/GoogleChrome/puppeteer/blob/master/examples/custom-chromium-revision.js))
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2. Puppeteer creates its own Chromium user profile which it cleans up on every run.
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3. Puppeteer sets an initial page size to 400px x 300px, which defines the screenshot size. The page size can be changed with `Page.setViewportSize()` method
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## API
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[API documentation](docs/api.md) is a work in progress.
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## Contributing
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Check out our [contributing guide](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md)
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# FAQ
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#### Q: What is Puppeteer?
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Puppeteer is a light-weight Node module to control headless Chrome using the [DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/).
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#### Q: Does Puppeteer work with headless Chromium?
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Yes. Puppeteer bundles a version of Chromium and runs it in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome) by default.
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#### Q: How is Puppeteer different than PhantomJS?
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While PhantomJS provides a JavaScript API to control a full-fledged browser (WebKit), Puppeteer is a light-weight Node module to control headless Chrome.
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Other important differences:
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- Uses an evergreen browser - Puppeteer uses headless Chromium, which means it can access all the latest web platform features offered by the Blink rendering engine.
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- Improved debuggability - thanks to Node debugging in Chrome DevTools.
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#### Q: Which Chromium version does Puppeteer use?
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[TODO]
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#### Q: How do I migrate from PhantomJS to Puppeteer?
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There's no automatic way to migrate PhantomJS scripts to Node scripts with Puppeteer. For more information and some guidance, check out our [migration guide](#migration-guide).
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#### Q: Why do most of the API methods return promises?
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Since Puppeteer's code is run by Node, it exists out-of-process to the controlled Chromium instance. This requires most of the API calls to be asynchronous to allow the necessary roundtrips to the browser.
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However, if you're using Node 8 or higher, `async/await` make life easier:
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```javascript
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browser.newPage().then(async page => {
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await page.setViewportSize({width: 1000, height: 1000});
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await page.printToPDF('blank.pdf');
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browser.close();
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});
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```
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#### Q: What is the "Phantom Shim"?
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"Phantom Shim" is a layer built atop the Puppeteer API that simulates Phantom's environment.
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Puppeteer's process model is different than Phantom's. Puppeteer runs out-of-process to the browser, whereas Phantom runs in-process. To simulate in-process behavior, phantom_shim hacks Node's runtime with [nested event loops](https://github.com/abbr/deasync)) to simulate in-process operation. This might result in unpredictable side-effects and makes the shim unreliable for certain use cases situations.
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#### Q: What is the difference between Puppeteer and Selenium / WebDriver?
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Selenium / WebDriver is a well-established cross-browser API that is useful for testing cross-browser support.
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Puppeteer is useful for single-browser testing. For example, many teams only run unit tests with a single browser (e.g. Phantom). In non-testing use cases, Puppeteer provides a powerful but simple API because it's only targeting one browser that enables you to rapidly develop automation scripts.
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# Migration Guide
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[TODO]
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