puppeteer/README.md
2017-07-13 21:47:48 -07:00

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Puppeteer Build Status

Puppeteer is a Node library which provides a high-level API to control Chromium over the DevTools Protocol. Puppeteer is inspired by PhantomJS. Check our FAQ to learn more.

Use Cases

  • Up-to-date testing environment that supports the latest Javascript features.
  • Crawl your site to generate pre-rendered content for your SPA.
  • Scrape content from websites.

Installation

Get the source:

git clone https://github.com/GoogleChrome/puppeteer
cd puppeteer

Install the dependencies:

yarn

or use npm:

npm install

Note: Puppeteer bundles Chromium (~70Mb) which it is guaranteed to work with. However, you're free to point Puppeteer to any Chromium executable (example)

Getting Started

The following script navigates to https://example.com and saves a screenshot to example.png:

const Browser = require('Puppeteer').Browser;
const browser = new Browser();

browser.newPage().then(async page => {
  await page.navigate('https://example.com');
  await page.screenshot({path: 'example.png'});
  browser.close();
});

A few notes:

  1. By default, Puppeteer runs a bundled Chromium browser. However, you can point Puppeteer to a different executable (example)
  2. Puppeteer creates its own Chromium user profile which it cleans up on every run.
  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

API

API documentation is a work in progress.

Contributing

Check out our contributing guide

FAQ

Q: What is Puppeteer?

Puppeteer is a light-weight Node module to control headless Chrome using the DevTools Protocol.

Q: Does Puppeteer work with headless Chromium?

Yes. Puppeteer bundles a version of Chromium and runs it in headless mode by default.

Q: How is Puppeteer different than PhantomJS?

While PhantomJS provides a JavaScript API to control a full-fledged browser (WebKit), Puppeteer is a light-weight Node module to control headless Chrome.

Other important differences:

  • 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.
  • Improved debuggability - thanks to Node debugging in Chrome DevTools.

Q: Which Chromium version does Puppeteer use?

[TODO]

Q: How do I migrate from PhantomJS to Puppeteer?

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.

Q: Why do most of the API methods return promises?

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.

However, if you're using Node 8 or higher, async/await make life easier:

browser.newPage().then(async page => {
  await page.setViewportSize({width: 1000, height: 1000});
  await page.printToPDF('blank.pdf');
  browser.close();
});

Q: What is the "Phantom Shim"?

"Phantom Shim" is a layer built atop the Puppeteer API that simulates Phantom's environment.

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) to simulate in-process operation. This might result in unpredictable side-effects and makes the shim unreliable for certain use cases situations.

Q: What is the difference between Puppeteer and Selenium / WebDriver?

Selenium / WebDriver is a well-established cross-browser API that is useful for testing cross-browser support.

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.

Migration Guide

[TODO]