1 | # Puppeteer
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4 | [![Linux Build Status](https://img.shields.io/travis/com/GoogleChrome/puppeteer/master.svg)](https://travis-ci.com/GoogleChrome/puppeteer) [![Windows Build Status](https://img.shields.io/appveyor/ci/aslushnikov/puppeteer/master.svg?logo=appveyor)](https://ci.appveyor.com/project/aslushnikov/puppeteer/branch/master) [![Build Status](https://api.cirrus-ci.com/github/GoogleChrome/puppeteer.svg)](https://cirrus-ci.com/github/GoogleChrome/puppeteer) [![NPM puppeteer package](https://img.shields.io/npm/v/puppeteer.svg)](https://npmjs.org/package/puppeteer)
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6 |
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7 | <img src="https://user-images.githubusercontent.com/10379601/29446482-04f7036a-841f-11e7-9872-91d1fc2ea683.png" height="200" align="right">
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8 |
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9 | ###### [API](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md) | [FAQ](#faq) | [Contributing](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md) | [Troubleshooting](https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md)
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11 | > Puppeteer is a Node library which provides a high-level API to control Chrome or Chromium over the [DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/). Puppeteer runs [headless](https://developers.google.com/web/updates/2017/04/headless-chrome) by default, but can be configured to run full (non-headless) Chrome or Chromium.
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12 |
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13 |
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14 | ###### What can I do?
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15 |
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16 | Most things that you can do manually in the browser can be done using Puppeteer! Here are a few examples to get you started:
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17 |
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18 | * Generate screenshots and PDFs of pages.
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19 | * Crawl a SPA (Single-Page Application) and generate pre-rendered content (i.e. "SSR" (Server-Side Rendering)).
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20 | * Automate form submission, UI testing, keyboard input, etc.
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21 | * 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.
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22 | * Capture a [timeline trace](https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/reference) of your site to help diagnose performance issues.
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23 | * Test Chrome Extensions.
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24 |
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25 |
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26 | Give it a spin: https://try-puppeteer.appspot.com/
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27 |
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28 |
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29 | ## Getting Started
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30 |
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31 | ### Installation
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32 |
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33 | To use Puppeteer in your project, run:
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34 |
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35 | ```bash
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36 | npm i puppeteer
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37 | # or "yarn add puppeteer"
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38 | ```
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39 |
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40 | Note: When you install Puppeteer, it downloads a recent version of Chromium (~170MB Mac, ~282MB Linux, ~280MB Win) that is guaranteed to work with the API. To skip the download, see [Environment variables](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md#environment-variables).
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41 |
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42 |
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43 | ### puppeteer-core
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44 |
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45 | Since version 1.7.0 we publish the [`puppeteer-core`](https://www.npmjs.com/package/puppeteer-core) package,
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46 | a version of Puppeteer that doesn't download Chromium by default.
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47 |
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48 | ```bash
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49 | npm i puppeteer-core
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50 | # or "yarn add puppeteer-core"
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51 | ```
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52 |
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53 | `puppeteer-core` is intended to be a lightweight version of Puppeteer for launching an existing browser installation or for connecting to a remote one. Be sure that the version of puppeteer-core you install is compatible with the
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54 | browser you intend to connect to.
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55 |
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56 | See [puppeteer vs puppeteer-core](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteer-vs-puppeteer-core).
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57 |
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58 | ### Usage
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59 |
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60 | Note: Puppeteer requires at least Node v6.4.0, but the examples below use async/await which is only supported in Node v7.6.0 or greater.
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61 |
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62 | Puppeteer will be familiar to people using other browser testing frameworks. You create an instance
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63 | of `Browser`, open pages, and then manipulate them with [Puppeteer's API](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md#).
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64 |
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65 | **Example** - navigating to https://example.com and saving a screenshot as *example.png*:
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66 |
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67 | Save file as **example.js**
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68 |
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69 | ```js
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70 | const puppeteer = require('puppeteer');
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71 |
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72 | (async () => {
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73 | const browser = await puppeteer.launch();
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74 | const page = await browser.newPage();
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75 | await page.goto('https://example.com');
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76 | await page.screenshot({path: 'example.png'});
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77 |
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78 | await browser.close();
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79 | })();
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80 | ```
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81 |
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82 | Execute script on the command line
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83 |
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84 | ```bash
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85 | node example.js
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86 | ```
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87 |
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88 | 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/v1.17.0/docs/api.md#pagesetviewportviewport).
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89 |
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90 | **Example** - create a PDF.
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91 |
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92 | Save file as **hn.js**
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93 |
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94 | ```js
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95 | const puppeteer = require('puppeteer');
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96 |
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97 | (async () => {
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98 | const browser = await puppeteer.launch();
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99 | const page = await browser.newPage();
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100 | await page.goto('https://news.ycombinator.com', {waitUntil: 'networkidle2'});
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101 | await page.pdf({path: 'hn.pdf', format: 'A4'});
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102 |
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103 | await browser.close();
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104 | })();
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105 | ```
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106 |
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107 | Execute script on the command line
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108 |
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109 | ```bash
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110 | node hn.js
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111 | ```
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112 |
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113 | See [`Page.pdf()`](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md#pagepdfoptions) for more information about creating pdfs.
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114 |
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115 | **Example** - evaluate script in the context of the page
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116 |
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117 | Save file as **get-dimensions.js**
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118 |
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119 | ```js
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120 | const puppeteer = require('puppeteer');
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121 |
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122 | (async () => {
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123 | const browser = await puppeteer.launch();
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124 | const page = await browser.newPage();
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125 | await page.goto('https://example.com');
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126 |
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127 | // Get the "viewport" of the page, as reported by the page.
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128 | const dimensions = await page.evaluate(() => {
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129 | return {
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130 | width: document.documentElement.clientWidth,
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131 | height: document.documentElement.clientHeight,
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132 | deviceScaleFactor: window.devicePixelRatio
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133 | };
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134 | });
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135 |
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136 | console.log('Dimensions:', dimensions);
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137 |
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138 | await browser.close();
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139 | })();
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140 | ```
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141 |
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142 | Execute script on the command line
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143 |
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144 | ```bash
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145 | node get-dimensions.js
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146 | ```
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147 |
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148 | See [`Page.evaluate()`](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md#pageevaluatepagefunction-args) for more information on `evaluate` and related methods like `evaluateOnNewDocument` and `exposeFunction`.
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149 |
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150 |
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151 |
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152 |
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153 | ## Default runtime settings
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154 |
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155 | **1. Uses Headless mode**
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156 |
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157 | 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/v1.17.0/docs/api.md#puppeteerlaunchoptions) when launching a browser:
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158 |
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159 | ```js
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160 | const browser = await puppeteer.launch({headless: false}); // default is true
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161 | ```
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162 |
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163 | **2. Runs a bundled version of Chromium**
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164 |
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165 | By default, Puppeteer downloads and uses a specific version of Chromium so its API
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166 | is guaranteed to work out of the box. To use Puppeteer with a different version of Chrome or Chromium,
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167 | pass in the executable's path when creating a `Browser` instance:
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168 |
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169 | ```js
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170 | const browser = await puppeteer.launch({executablePath: '/path/to/Chrome'});
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171 | ```
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172 |
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173 | See [`Puppeteer.launch()`](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md#puppeteerlaunchoptions) for more information.
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174 |
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175 | See [`this article`](https://www.howtogeek.com/202825/what%E2%80%99s-the-difference-between-chromium-and-chrome/) for a description of the differences between Chromium and Chrome. [`This article`](https://chromium.googlesource.com/chromium/src/+/master/docs/chromium_browser_vs_google_chrome.md) describes some differences for Linux users.
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176 |
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177 | **3. Creates a fresh user profile**
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178 |
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179 | Puppeteer creates its own Chromium user profile which it **cleans up on every run**.
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180 |
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181 |
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182 |
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183 | ## Resources
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184 |
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185 | - [API Documentation](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md)
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186 | - [Examples](https://github.com/GoogleChrome/puppeteer/tree/master/examples/)
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187 | - [Community list of Puppeteer resources](https://github.com/transitive-bullshit/awesome-puppeteer)
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188 |
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189 |
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190 |
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191 |
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192 | ## Debugging tips
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193 |
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194 | 1. Turn off headless mode - sometimes it's useful to see what the browser is
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195 | displaying. Instead of launching in headless mode, launch a full version of
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196 | the browser using `headless: false`:
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197 |
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198 | const browser = await puppeteer.launch({headless: false});
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199 |
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200 | 2. Slow it down - the `slowMo` option slows down Puppeteer operations by the
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201 | specified amount of milliseconds. It's another way to help see what's going on.
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202 |
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203 | const browser = await puppeteer.launch({
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204 | headless: false,
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205 | slowMo: 250 // slow down by 250ms
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206 | });
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207 |
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208 | 3. Capture console output - You can listen for the `console` event.
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209 | This is also handy when debugging code in `page.evaluate()`:
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210 |
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211 | page.on('console', msg => console.log('PAGE LOG:', msg.text()));
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212 |
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213 | await page.evaluate(() => console.log(`url is ${location.href}`));
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214 |
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215 | 4. Use debugger in application code browser
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216 |
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217 | There are two execution context: node.js that is running test code, and the browser
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218 | running application code being tested. This lets you debug code in the
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219 | application code browser; ie code inside `evaluate()`.
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220 |
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221 | - Use `{devtools: true}` when launching Puppeteer:
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222 |
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223 | `const browser = await puppeteer.launch({devtools: true});`
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224 |
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225 | - Change default test timeout:
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226 |
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227 | jest: `jest.setTimeout(100000);`
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228 |
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229 | jasmine: `jasmine.DEFAULT_TIMEOUT_INTERVAL = 100000;`
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230 |
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231 | mocha: `this.timeout(100000);` (don't forget to change test to use [function and not '=>'](https://stackoverflow.com/a/23492442))
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232 |
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233 | - Add an evaluate statement with `debugger` inside / add `debugger` to an existing evaluate statement:
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234 |
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235 | `await page.evaluate(() => {debugger;});`
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236 |
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237 | The test will now stop executing in the above evaluate statement, and chromium will stop in debug mode.
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238 |
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239 | 5. Use debugger in node.js
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240 |
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241 | This will let you debug test code. For example, you can step over `await page.click()` in the node.js script and see the click happen in the application code browser.
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242 |
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243 | Note that you won't be able to run `await page.click()` in
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244 | DevTools console due to this [Chromium bug](https://bugs.chromium.org/p/chromium/issues/detail?id=833928). So if
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245 | you want to try something out, you have to add it to your test file.
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246 |
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247 | - Add `debugger;` to your test, eg:
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248 | ```
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249 | debugger;
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250 | await page.click('a[target=_blank]');
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251 | ```
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252 | - Set `headless` to `false`
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253 | - Run `node --inspect-brk`, eg `node --inspect-brk node_modules/.bin/jest tests`
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254 | - In Chrome open `chrome://inspect/#devices` and click `inspect`
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255 | - In the newly opened test browser, type `F8` to resume test execution
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256 | - Now your `debugger` will be hit and you can debug in the test browser
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257 |
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258 |
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259 | 6. Enable verbose logging - internal DevTools protocol traffic
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260 | will be logged via the [`debug`](https://github.com/visionmedia/debug) module under the `puppeteer` namespace.
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261 |
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262 | # Basic verbose logging
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263 | env DEBUG="puppeteer:*" node script.js
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264 |
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265 | # Protocol traffic can be rather noisy. This example filters out all Network domain messages
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266 | env DEBUG="puppeteer:*" env DEBUG_COLORS=true node script.js 2>&1 | grep -v '"Network'
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267 |
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268 | 7. Debug your Puppeteer (node) code easily, using [ndb](https://github.com/GoogleChromeLabs/ndb)
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269 |
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270 | - `npm install -g ndb` (or even better, use [npx](https://github.com/zkat/npx)!)
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271 |
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272 | - add a `debugger` to your Puppeteer (node) code
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273 |
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274 | - add `ndb` (or `npx ndb`) before your test command. For example:
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275 |
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276 | `ndb jest` or `ndb mocha` (or `npx ndb jest` / `npx ndb mocha`)
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277 |
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278 | - debug your test inside chromium like a boss!
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279 |
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280 |
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281 |
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282 |
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283 | ## Contributing to Puppeteer
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284 |
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285 | Check out [contributing guide](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md) to get an overview of Puppeteer development.
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286 |
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287 |
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288 |
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289 | # FAQ
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290 |
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291 | #### Q: Who maintains Puppeteer?
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292 |
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293 | The Chrome DevTools team maintains the library, but we'd love your help and expertise on the project!
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294 | See [Contributing](https://github.com/GoogleChrome/puppeteer/blob/master/CONTRIBUTING.md).
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295 |
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296 | #### Q: What are Puppeteer’s goals and principles?
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297 |
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298 | The goals of the project are:
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299 |
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300 | - Provide a slim, canonical library that highlights the capabilities of the [DevTools Protocol](https://chromedevtools.github.io/devtools-protocol/).
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301 | - Provide a reference implementation for similar testing libraries. Eventually, these other frameworks could adopt Puppeteer as their foundational layer.
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302 | - Grow the adoption of headless/automated browser testing.
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303 | - Help dogfood new DevTools Protocol features...and catch bugs!
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304 | - Learn more about the pain points of automated browser testing and help fill those gaps.
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305 |
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306 | We adapt [Chromium principles](https://www.chromium.org/developers/core-principles) to help us drive product decisions:
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307 | - **Speed**: Puppeteer has almost zero performance overhead over an automated page.
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308 | - **Security**: Puppeteer operates off-process with respect to Chromium, making it safe to automate potentially malicious pages.
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309 | - **Stability**: Puppeteer should not be flaky and should not leak memory.
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310 | - **Simplicity**: Puppeteer provides a high-level API that’s easy to use, understand, and debug.
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311 |
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312 | #### Q: Is Puppeteer replacing Selenium/WebDriver?
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313 |
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314 | **No**. Both projects are valuable for very different reasons:
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315 | - Selenium/WebDriver focuses on cross-browser automation; its value proposition is a single standard API that works across all major browsers.
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316 | - Puppeteer focuses on Chromium; its value proposition is richer functionality and higher reliability.
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317 |
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318 | That said, you **can** use Puppeteer to run tests against Chromium, e.g. using the community-driven [jest-puppeteer](https://github.com/smooth-code/jest-puppeteer). While this probably shouldn’t be your only testing solution, it does have a few good points compared to WebDriver:
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319 |
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320 | - Puppeteer requires zero setup and comes bundled with the Chromium version it works best with, making it [very easy to start with](https://github.com/GoogleChrome/puppeteer/#getting-started). At the end of the day, it’s better to have a few tests running chromium-only, than no tests at all.
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321 | - Puppeteer has event-driven architecture, which removes a lot of potential flakiness. There’s no need for evil “sleep(1000)” calls in puppeteer scripts.
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322 | - Puppeteer runs headless by default, which makes it fast to run. Puppeteer v1.5.0 also exposes browser contexts, making it possible to efficiently parallelize test execution.
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323 | - Puppeteer shines when it comes to debugging: flip the “headless” bit to false, add “slowMo”, and you’ll see what the browser is doing. You can even open Chrome DevTools to inspect the test environment.
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324 |
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325 | #### Q: Why doesn’t Puppeteer v.XXX work with Chromium v.YYY?
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326 |
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327 | We see Puppeteer as an **indivisible entity** with Chromium. Each version of Puppeteer bundles a specific version of Chromium – **the only** version it is guaranteed to work with.
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328 |
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329 | This is not an artificial constraint: A lot of work on Puppeteer is actually taking place in the Chromium repository. Here’s a typical story:
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330 | - A Puppeteer bug is reported: https://github.com/GoogleChrome/puppeteer/issues/2709
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331 | - It turned out this is an issue with the DevTools protocol, so we’re fixing it in Chromium: https://chromium-review.googlesource.com/c/chromium/src/+/1102154
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332 | - Once the upstream fix is landed, we roll updated Chromium into Puppeteer: https://github.com/GoogleChrome/puppeteer/pull/2769
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333 |
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334 | However, oftentimes it is desirable to use Puppeteer with the official Google Chrome rather than Chromium. For this to work, you should install a `puppeteer-core` version that corresponds to the Chrome version.
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335 |
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336 | For example, in order to drive Chrome 71 with puppeteer-core, use `chrome-71` npm tag:
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337 | ```bash
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338 | npm install puppeteer-core@chrome-71
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339 | ```
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340 |
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341 | #### Q: Which Chromium version does Puppeteer use?
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342 |
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343 | Look for `chromium_revision` in [package.json](https://github.com/GoogleChrome/puppeteer/blob/master/package.json).
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344 |
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345 | #### Q: What’s considered a “Navigation”?
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346 |
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347 | From Puppeteer’s standpoint, **“navigation” is anything that changes a page’s URL**.
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348 | Aside from regular navigation where the browser hits the network to fetch a new document from the web server, this includes [anchor navigations](https://www.w3.org/TR/html5/single-page.html#scroll-to-fragid) and [History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API) usage.
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349 |
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350 | With this definition of “navigation,” **Puppeteer works seamlessly with single-page applications.**
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351 |
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352 | #### Q: What’s the difference between a “trusted" and "untrusted" input event?
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353 |
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354 | In browsers, input events could be divided into two big groups: trusted vs. untrusted.
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355 |
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356 | - **Trusted events**: events generated by users interacting with the page, e.g. using a mouse or keyboard.
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357 | - **Untrusted event**: events generated by Web APIs, e.g. `document.createEvent` or `element.click()` methods.
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358 |
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359 | Websites can distinguish between these two groups:
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360 | - using an [`Event.isTrusted`](https://developer.mozilla.org/en-US/docs/Web/API/Event/isTrusted) event flag
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361 | - sniffing for accompanying events. For example, every trusted `'click'` event is preceded by `'mousedown'` and `'mouseup'` events.
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362 |
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363 | For automation purposes it’s important to generate trusted events. **All input events generated with Puppeteer are trusted and fire proper accompanying events.** If, for some reason, one needs an untrusted event, it’s always possible to hop into a page context with `page.evaluate` and generate a fake event:
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364 |
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365 | ```js
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366 | await page.evaluate(() => {
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367 | document.querySelector('button[type=submit]').click();
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368 | });
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369 | ```
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370 |
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371 | #### Q: What features does Puppeteer not support?
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372 |
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373 | You may find that Puppeteer does not behave as expected when controlling pages that incorporate audio and video. (For example, [video playback/screenshots is likely to fail](https://github.com/GoogleChrome/puppeteer/issues/291).) There are two reasons for this:
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374 |
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375 | * Puppeteer is bundled with Chromium--not Chrome--and so by default, it inherits all of [Chromium's media-related limitations](https://www.chromium.org/audio-video). This means that Puppeteer does not support licensed formats such as AAC or H.264. (However, it is possible to force Puppeteer to use a separately-installed version Chrome instead of Chromium via the [`executablePath` option to `puppeteer.launch`](https://github.com/GoogleChrome/puppeteer/blob/v1.17.0/docs/api.md#puppeteerlaunchoptions). You should only use this configuration if you need an official release of Chrome that supports these media formats.)
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376 | * Since Puppeteer (in all configurations) controls a desktop version of Chromium/Chrome, features that are only supported by the mobile version of Chrome are not supported. This means that Puppeteer [does not support HTTP Live Streaming (HLS)](https://caniuse.com/#feat=http-live-streaming).
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377 |
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378 | #### Q: I am having trouble installing / running Puppeteer in my test environment. Where should I look for help?
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379 | We have a [troubleshooting](https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md) guide for various operating systems that lists the required dependencies.
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380 |
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381 | #### Q: How do I try/test a prerelease version of Puppeteer?
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382 |
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383 | You can check out this repo or install the latest prerelease from npm:
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384 |
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385 | ```bash
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386 | npm i --save puppeteer@next
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387 | ```
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388 |
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389 | Please note that prerelease may be unstable and contain bugs.
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390 |
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391 | #### Q: I have more questions! Where do I ask?
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392 |
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393 | There are many ways to get help on Puppeteer:
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394 | - [bugtracker](https://github.com/GoogleChrome/puppeteer/issues)
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395 | - [stackoverflow](https://stackoverflow.com/questions/tagged/puppeteer)
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396 | - [slack channel](https://join.slack.com/t/puppeteer/shared_invite/enQtMzU4MjIyMDA5NTM4LTM1OTdkNDhlM2Y4ZGUzZDdjYjM5ZWZlZGFiZjc4MTkyYTVlYzIzYjU5NDIyNzgyMmFiNDFjN2UzNWU0N2ZhZDc)
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397 |
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398 | Make sure to search these channels before posting your question.
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399 |
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400 |
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401 |
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