Chrome Launcher

Launch Google Chrome with ease from node.

• Disables many Chrome services that add noise to automated scenarios
• 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.

Installing

1yarn add chrome-launcher
2
3# or with npm:
4npm install chrome-launcher

API

.launch([opts])

Launch options

1{
2  // (optional) remote debugging port number to use. If provided port is already busy, launch() will reject
3  // Default: an available port is autoselected
4  port: number;
5
6  // (optional) When `port` is specified *and* no Chrome is found at that port,
7  // * if `false` (default), chrome-launcher will launch a new Chrome with that port.
8  // * if `true`, throw an error
9  // This option is useful when you wish to explicitly connect to a running Chrome, such as on a mobile device via adb
10  // Default: false
11  portStrictMode: boolean;
12
13  // (optional) Additional flags to pass to Chrome, for example: ['--headless', '--disable-gpu']
14  // See: https://github.com/GoogleChrome/chrome-launcher/blob/main/docs/chrome-flags-for-tools.md
15  // Do note, many flags are set by default: https://github.com/GoogleChrome/chrome-launcher/blob/main/src/flags.ts
16  chromeFlags: Array<string>;
17
18  // (optional) Additional preferences to be set in Chrome, for example: {'download.default_directory': __dirname}
19  // See: https://chromium.googlesource.com/chromium/src/+/main/chrome/common/pref_names.cc
20  // Do note, if you set preferences when using your default profile it will overwrite these
21  prefs: {[key: string]: Object};
22
23  // (optional) Close the Chrome process on `Ctrl-C`
24  // Default: true
25  handleSIGINT: boolean;
26
27  // (optional) Explicit path of intended Chrome binary
28  // * If this `chromePath` option is defined, it will be used.
29  // * Otherwise, the `CHROME_PATH` env variable will be used if set. (`LIGHTHOUSE_CHROMIUM_PATH` is deprecated)
30  // * Otherwise, a detected Chrome Canary will be used if found
31  // * Otherwise, a detected Chrome (stable) will be used
32  chromePath: string;
33
34  // (optional) Chrome profile path to use, if set to `false` then the default profile will be used.
35  // By default, a fresh Chrome profile will be created
36  userDataDir: string | boolean;
37
38  // (optional) Starting URL to open the browser with
39  // Default: `about:blank`
40  startingUrl: string;
41
42  // (optional) Logging level
43  // Default: 'silent'
44  logLevel: 'verbose'|'info'|'error'|'silent';
45
46  // (optional) Flags specific in [flags.ts](src/flags.ts) will not be included.
47  // Typically used with the defaultFlags() method and chromeFlags option.
48  // Default: false
49  ignoreDefaultFlags: boolean;
50
51  // (optional) Interval in ms, which defines how often launcher checks browser port to be ready.
52  // Default: 500
53  connectionPollInterval: number;
54
55  // (optional) A number of retries, before browser launch considered unsuccessful.
56  // Default: 50
57  maxConnectionRetries: number;
58
59  // (optional) A dict of environmental key value pairs to pass to the spawned chrome process.
60  envVars: {[key: string]: string};
61};

Launched chrome interface

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

1// The remote debugging port exposed by the launched chrome
2chrome.port: number;
3
4// Method to kill Chrome (and cleanup the profile folder)
5chrome.kill: () => Promise<void>;
6
7// The process id
8chrome.pid: number;
9
10// The childProcess object for the launched Chrome
11chrome.process: childProcess
12
13// If chromeFlags contains --remote-debugging-pipe. Otherwise remoteDebuggingPipes is null.
14chrome.remoteDebuggingPipes.incoming: ReadableStream
15chrome.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.

ChromeLauncher.Launcher.defaultFlags()

Returns an Array<string> 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.

ChromeLauncher.Launcher.getInstallations()

Returns an Array<string> 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.

.killAll()

Attempts to kill all Chrome instances created with .launch([opts]). 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.

1import * as ChromeLauncher from 'chrome-launcher';
2
3async function cleanup() {
4  await ChromeLauncher.killAll();
5}

Examples

Launching chrome:

1import * as ChromeLauncher from 'chrome-launcher';
2
3ChromeLauncher.launch({
4  startingUrl: 'https://google.com'
5}).then(chrome => {
6  console.log(`Chrome debugging port running on ${chrome.port}`);
7});

Launching headless chrome:

1import * as ChromeLauncher from 'chrome-launcher';
2
3ChromeLauncher.launch({
4  startingUrl: 'https://google.com',
5  chromeFlags: ['--headless', '--disable-gpu']
6}).then(chrome => {
7  console.log(`Chrome debugging port running on ${chrome.port}`);
8});

Launching with support for extensions and audio:

1import * as ChromeLauncher from 'chrome-launcher';
2
3const newFlags = ChromeLauncher.Launcher.defaultFlags().filter(flag => flag !== '--disable-extensions' && flag !== '--mute-audio');
4
5ChromeLauncher.launch({
6  ignoreDefaultFlags: true,
7  chromeFlags: newFlags,
8}).then(chrome => { ... });

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

Continuous Integration

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:

1language: node_js
2install:
3  - yarn install
4before_script:
5  - export DISPLAY=:99.0
6  - export CHROME_PATH="$(pwd)/chrome-linux/chrome"
7  - sh -e /etc/init.d/xvfb start
8  - sleep 3 # wait for xvfb to boot
9
10addons:
11  chrome: stable