mirror of
https://github.com/puppeteer/puppeteer
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99 lines
5.1 KiB
Markdown
99 lines
5.1 KiB
Markdown
# Puppeteer [](https://travis-ci.com/GoogleChrome/puppeteer)
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<img src="https://user-images.githubusercontent.com/238208/28749789-e67693de-7487-11e7-85f9-2d9ad9025aae.png" height="150" align="right">
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###### [API](docs/api.md) | [FAQ](#faq) | [Contributing](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md)
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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.
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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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To add Puppeteer to your project, run:
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```
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yarn add puppeteer
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```
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> **NOTE** Puppeteer bundles a version of Chromium (~90Mb) 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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To navigate to https://example.com and save a screenshot as *example.png*, save the following script as `example.js` and run it using `node example.js`:
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```js
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const {Browser} = require('puppeteer');
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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 bundles chromium browser with which it works best. 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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4. By default, browser is launched in a headless mode. This could be changed via ['headless' browser option](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#new-browseroptions)
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## API Documentation
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Explore the [API documentation](docs/api.md) and [examples](https://github.com/GoogleChrome/puppeteer/tree/master/examples/) to learn more.
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## Contributing to Puppeteer
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Check out [contributing guide](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md) to get an overview of puppeteer development.
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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: Which Chromium version does Puppeteer use?
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Puppeteer bundles chromium it works best with. As chromium improves over time, new versions of puppeteer will be released which depend on a newer chromium versions.
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Current chromium version is declared in [package.json](https://github.com/GoogleChrome/puppeteer/blob/master/package.json) as `chromium_revision` field.
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#### Q: Does Puppeteer work with headless Chromium?
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Yes. Puppeteer runs chromium in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome) by default.
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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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It is recommended to use `async/await` to consume asynchronous api:
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```js
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const {Browser} = require('puppeteer');
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const browser = new Browser();
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browser.newPage().then(async page => {
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await page.setViewport({width: 1000, height: 1000});
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await page.pdf({path: '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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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.
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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.
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> **NOTE** It is strictly **not recommended** to use PhantomShim out in the wild.
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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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