Chrome Launcher  

Launch Google Chrome with ease from node.

* Disables many Chrome services that add noise to automated scenarios
* See our chrome-flags-for-tools.md doc for an in-depth accounting of Chrome flags that are useful for measurement/automation tools.
* Opens up the browser's remote-debugging-port on an available port
* Automagically locates a Chrome binary to launch
* Uses a fresh Chrome profile for each launch, and cleans itself up on kill()
* Binds Ctrl-C (by default) to terminate the Chrome process
* Exposes a small set of options for configurability over these details

Once launched, interacting with the browser must be done over the devtools protocol, typically via chrome-remote-interface. For many cases Puppeteer is recommended, though it has its own chrome launching mechanism.

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``sh
yarn add chrome-launcher

or with npm:


npm install chrome-launcher
`

API

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#### Launch options

`js
{
// (optional) remote debugging port number to use. If provided port is already busy, launch() will reject
// Default: an available port is autoselected
port: number;

// (optional) When port is specified and no Chrome is found at that port,
// * if false (default), chrome-launcher will launch a new Chrome with that port.
// * if true, throw an error
// This option is useful when you wish to explicitly connect to a running Chrome, such as on a mobile device via adb
// Default: false
portStrictMode: boolean;

// (optional) Additional flags to pass to Chrome, for example: ['--headless', '--disable-gpu']
// See: https://github.com/GoogleChrome/chrome-launcher/blob/main/docs/chrome-flags-for-tools.md
// Do note, many flags are set by default: https://github.com/GoogleChrome/chrome-launcher/blob/main/src/flags.ts
chromeFlags: Array;

// (optional) Additional preferences to be set in Chrome, for example: {'download.default_directory': __dirname}
// See: https://chromium.googlesource.com/chromium/src/+/main/chrome/common/pref_names.cc
// Do note, if you set preferences when using your default profile it will overwrite these
prefs: {[key: string]: Object};

// (optional) Close the Chrome process on Ctrl-C
// Default: true
handleSIGINT: boolean;

// (optional) Explicit path of intended Chrome binary
 // * If this chromePath option is defined, it will be used.
// * Otherwise, the CHROME_PATH env variable will be used if set. (LIGHTHOUSE_CHROMIUM_PATH is deprecated)
 // * Otherwise, a detected Chrome Canary will be used if found
// * Otherwise, a detected Chrome (stable) will be used
chromePath: string;

// (optional) Chrome profile path to use, if set to false then the default profile will be used.
// By default, a fresh Chrome profile will be created
userDataDir: string | boolean;

// (optional) Starting URL to open the browser with
// Default: about:blank
startingUrl: string;

// (optional) Logging level
// Default: 'silent'
logLevel: 'verbose'|'info'|'error'|'silent';

// (optional) Flags specific in flags.ts will not be included.
// Typically used with the defaultFlags() method and chromeFlags option.
// Default: false
ignoreDefaultFlags: boolean;

// (optional) Interval in ms, which defines how often launcher checks browser port to be ready.
// Default: 500
connectionPollInterval: number;

// (optional) A number of retries, before browser launch considered unsuccessful.
// Default: 50
maxConnectionRetries: number;

// (optional) A dict of environmental key value pairs to pass to the spawned chrome process.
envVars: {[key: string]: string};
};
`

#### Launched chrome interface

#### .launch().then(chrome => ...

`js
// The remote debugging port exposed by the launched chrome
chrome.port: number;

// Method to kill Chrome (and cleanup the profile folder)
chrome.kill: () => Promise;

// The process id
chrome.pid: number;

// The childProcess object for the launched Chrome
chrome.process: childProcess

// If chromeFlags contains --remote-debugging-pipe. Otherwise remoteDebuggingPipes is null.
chrome.remoteDebuggingPipes.incoming: ReadableStream
chrome.remoteDebuggingPipes.outgoing: WritableStream
`

When --remote-debugging-pipe is passed via chromeFlags, then port will be
unusable (0) by default. Instead, debugging messages are exchanged via
remoteDebuggingPipes.incoming and remoteDebuggingPipes.outgoing. The data
in these pipes are JSON values terminated by a NULL byte (\x00).
Data written to remoteDebuggingPipes.outgoing are sent to Chrome,
data read from remoteDebuggingPipes.incoming are received from Chrome.

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Returns an Array of the default flags Chrome is launched with. Typically used along with the ignoreDefaultFlags and chromeFlags options.

Note: This array will exclude the following flags: --remote-debugging-port --disable-setuid-sandbox --user-data-dir.

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Returns an Array of paths to available Chrome installations. When chromePath is not provided to .launch(), the first installation returned from this method is used instead.

Note: This method performs synchronous I/O operations.

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Attempts to kill all Chrome instances created with [.launch([opts])](#launchopts). Returns a Promise that resolves to an array of errors that occurred while killing instances. If all instances were killed successfully, the array will be empty.

`js
import * as ChromeLauncher from 'chrome-launcher';

async function cleanup() {
await ChromeLauncher.killAll();
}
`

Examples

#### Launching chrome:

`js
import * as ChromeLauncher from 'chrome-launcher';

ChromeLauncher.launch({
startingUrl: 'https://google.com'
}).then(chrome => {
console.log(Chrome debugging port running on ${chrome.port});
});
`


#### Launching headless chrome:

`js
import * as ChromeLauncher from 'chrome-launcher';

ChromeLauncher.launch({
startingUrl: 'https://google.com',
chromeFlags: ['--headless', '--disable-gpu']
}).then(chrome => {
console.log(Chrome debugging port running on ${chrome.port});
});
`

#### Launching with support for extensions and audio:

`js
import * as ChromeLauncher from 'chrome-launcher';

const newFlags = ChromeLauncher.Launcher.defaultFlags().filter(flag => flag !== '--disable-extensions' && flag !== '--mute-audio');

ChromeLauncher.launch({
ignoreDefaultFlags: true,
chromeFlags: newFlags,
}).then(chrome => { ... });
`

To programatically load an extension at runtime, use --remote-debugging-pipe
as shown in test/load-extension-test.ts.

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In a CI environment like Travis, Chrome may not be installed. If you want to use chrome-launcher, Travis can install Chrome at run time with an addon. Alternatively, you can also install Chrome using the download-chrome.sh script.

Then in .travis.yml, use it like so:

`yaml
language: node_js
install:
- yarn install
before_script:
- export DISPLAY=:99.0
- export CHROME_PATH="$(pwd)/chrome-linux/chrome"
- sh -e /etc/init.d/xvfb start
- sleep 3 # wait for xvfb to boot

addons:
chrome: stable
``