puppeteer/README.md

# Puppeteer [![Build Status](https://travis-ci.com/GoogleChrome/puppeteer.svg?token=8jabovWqb8afz5RDcYqx&branch=master)](https://travis-ci.com/GoogleChrome/puppeteer)

<img src="https://user-images.githubusercontent.com/238208/28749789-e67693de-7487-11e7-85f9-2d9ad9025aae.png" height="150" align="right">

###### [API](docs/api.md) | [FAQ](#faq) | [Contributing](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md)

Puppeteer is a Node library which provides a high-level API to control [headless](https://developers.google.com/web/updates/2017/04/headless-chrome) Chrome over the [DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/). It can also be configured to use full (non-headless) Chrome.

###### What can I do?

Most things that you can do manually in the browser can be done using Puppeteer! Here are a few examples to get you started:

* Generate screenshots and PDFs of pages.
* Crawl a SPA and generate pre-rendered content (i.e. "SSR").
* Scrape content from websites.
* Automate form submission, UI testing, keyboard input, etc.
* Create an up-to-date, automated testing environment. Run your tests directly in the latest version of Chrome using the latest JavaScript and browser features.
* Capture a [timeline trace](https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/reference) of your site to help diagnose performance issues.

## Getting Started

### Installation

*Puppeteer requires Node version 7.10 or greater*

To use Puppeteer in your project, run:
```
yarn add puppeteer
# or "npm i puppeteer"
```

> **Note**: When you install Puppeteer, it downloads a recent version of Chromium (~71Mb Mac, ~90Mb Linux, ~110Mb Win) that is guaranteed to work with the API. However, you can [tell Puppeteer to use any Chromium executable](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#new-browseroptions) installed on the machine.

### Usage

Puppeteer will be familiar to using other browser testing frameworks. You create an instance
of `Browser`, open pages, and then manipulate them with [Puppeteer's API]((https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#).

**Example** - navigating to https://example.com and saving a screenshot as *example.png*:

```js
const {Browser} = require('puppeteer');
const browser = new Browser();

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

browser.close();
})();
```

or, without `async`/`await`:

```js
const {Browser} = require('puppeteer');
const browser = new Browser();

browser.newPage().then(page => {
  page.goto('https://example.com').then(response => {
     page.screenshot({path: 'example.png'}).then(buffer => {
       browser.close();
     });
  });
});
```

Puppeteer sets an initial page size to 800px x 600px, which defines the screenshot size. The page size can be customized  with [`Page.setViewport()`](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#pagesetviewportviewport).

**Example** - create a PDF.

```js
const {Browser} = require('puppeteer');
const browser = new Browser();

(async() => {
const page = await browser.newPage();
await page.goto('https://news.ycombinator.com', {waitUntil: 'networkidle'});
await page.pdf({path: 'hn.pdf', format: 'A4'});

browser.close();
})();
```

See [`Page.pdf()`](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#pagepdfoptions) for more information about creating pdfs.

## Default runtime settings

**Uses Headless mode**

Puppeteer launches Chromium in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). To launch a full version of Chromium, set the ['headless' option](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#new-browseroptions) when creating a browser:

```js
const browser = new Browser({headless: false});
```

**Runs a bundled version of Chromium**

By default, Puppeteer downloads and uses a specific version of Chromium but it can be configured to [use another install of Chrome](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#new-browseroptions)

**Creates a fresh user profile**

Puppeteer creates its own Chromium user profile which it **cleans up on every run**.

## API Documentation

Explore the [API documentation](docs/api.md) and [examples](https://github.com/GoogleChrome/puppeteer/tree/master/examples/) to learn more.

## Contributing to Puppeteer

Check out [contributing guide](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md) to get an overview of puppeteer development.

# FAQ

#### Q: What is Puppeteer?

Puppeteer is a light-weight Node module to control headless Chrome using the latest version of the [DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/).

#### Q: Which Chromium version does Puppeteer use?

Look for `chromium_revision` in [package.json](https://github.com/GoogleChrome/puppeteer/blob/master/package.json).

Puppeteer bundles Chromium to insure that the latest features it uses are guaranteed to be available. As the DevTools protocol and browser improve over time, Puppeteer will be updated to depend on newer versions of Chromium.

#### Q: Does Puppeteer work with headless Chromium?

Yes. Puppeteer runs Chromium in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome) by default.

#### 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.

#### Q: What is the "Phantom Shim"?

To make sure Puppeteer's API is comprehensive, we built [PhantomShim](https://github.com/GoogleChrome/puppeteer/tree/master/phantom_shim) - a lightweight phantomJS script runner built atop of Puppeteer API. We run phantomJS tests against PhantomShim with an ultimate goal to pass them all.

To emulate PhantomJS which runs automation scripts in-process to the automated page, PhantomShim spawns [nested event loops](https://github.com/abbr/deasync). On practice, this might result in unpredictable side-effects and makes the shim unreliable, but this works pretty good for testing goals.

> **NOTE** It is strictly **not recommended** to use PhantomShim out in the wild.

#### 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.