Chrome Debugging Protocol interface that helps to instrument Chrome (or any other suitable implementation) by providing a simple abstraction of commands and notifications using a straightforward JavaScript API.
This module is one of the many third-party protocol clients.
The following snippet loads https://github.com
and dumps every request made:
const CDP = require('chrome-remote-interface');
async function example() {
let client;
try {
// connect to endpoint
client = await CDP();
// extract domains
const {Network, Page} = client;
// setup handlers
Network.requestWillBeSent((params) => {
console.log(params.request.url);
});
// enable events then start!
await Network.enable();
await Page.enable();
await Page.navigate({url: 'https://github.com'});
await Page.loadEventFired();
} catch (err) {
console.error(err);
} finally {
if (client) {
await client.close();
}
}
}
example();
Find more examples in the wiki. You may also want to take a look at the FAQ.
npm install chrome-remote-interface
Install globally (-g
) to just use the bundled client.
This module should work with every application implementing the Chrome Debugging Protocol. In particular, it has been tested against the following implementations:
Implementation | Protocol version | Protocol | List | New | Activate | Close | Version |
---|---|---|---|---|---|---|---|
Chrome | tip-of-tree | yes¹ | yes | yes | yes | yes | yes |
Opera | tip-of-tree | yes | yes | yes | yes | yes | yes |
Node.js (v6.3.0+) | node | yes | no | no | no | no | yes |
Safari (iOS) | partial | no | yes | no | no | no | no |
Edge | partial | yes | yes | no | no | no | yes |
Firefox (Nightly) | partial | yes | yes | no | yes | yes | yes |
¹ Not available on Chrome for Android.
The meaning of target varies according to the implementation, for example, each Chrome tab represents a target whereas for Node.js a target is the currently inspected script.
An instance of either Chrome itself or another implementation needs to be
running on a known port in order to use this module (defaults to
localhost:9222
).
Start Chrome with the --remote-debugging-port
option, for example:
google-chrome --remote-debugging-port=9222
Since version 59, additionally use the --headless
option, for example:
google-chrome --headless --remote-debugging-port=9222
Plug the device and enable the port forwarding, for example:
adb forward tcp:9222 localabstract:chrome_devtools_remote
In order to be inspectable, a WebView must be configured for debugging and the corresponding process ID must be known. There are several ways to obtain it, for example:
adb shell grep -a webview_devtools_remote /proc/net/unix
Finally, port forwarding can be enabled as follows:
adb forward tcp:9222 localabstract:webview_devtools_remote_<pid>
Start Opera with the --remote-debugging-port
option, for example:
opera --remote-debugging-port=9222
Start Node.js with the --inspect
option, for example:
node --inspect=9222 script.js
Install and run the iOS WebKit Debug Proxy. Then use it with the local
option set to true
to use the local version of the protocol or pass a custom
descriptor upon connection (protocol
option).
Start Edge with the --devtools-server-port
option, for example:
MicrosoftEdge.exe --devtools-server-port 9222 about:blank
Please find more information here.
Start Firefox with the --remote-debugging-port
option, for example:
firefox --remote-debugging-port 9222
Bear in mind that this is an experimental feature of Firefox.
This module comes with a bundled client application that can be used to interactively control a remote instance.
The bundled client exposes subcommands to interact with the HTTP frontend
(e.g., List, New, etc.),
run with --help
to display the list of available options.
Here are some examples:
$ chrome-remote-interface new 'http://example.com'
{
"description": "",
"devtoolsFrontendUrl": "/devtools/inspector.html?ws=localhost:9222/devtools/page/b049bb56-de7d-424c-a331-6ae44cf7ae01",
"id": "b049bb56-de7d-424c-a331-6ae44cf7ae01",
"thumbnailUrl": "/thumb/b049bb56-de7d-424c-a331-6ae44cf7ae01",
"title": "",
"type": "page",
"url": "http://example.com/",
"webSocketDebuggerUrl": "ws://localhost:9222/devtools/page/b049bb56-de7d-424c-a331-6ae44cf7ae01"
}
$ chrome-remote-interface close 'b049bb56-de7d-424c-a331-6ae44cf7ae01'
Using the inspect
subcommand it is possible to perform command execution
and event binding in a REPL fashion that provides completion.
Here is a sample session:
$ chrome-remote-interface inspect
>>> Runtime.evaluate({expression: 'window.location.toString()'})
{ result: { type: 'string', value: 'about:blank' } }
>>> Page.enable()
{}
>>> Page.loadEventFired(console.log)
[Function]
>>> Page.navigate({url: 'https://github.com'})
{ frameId: 'E1657E22F06E6E0BE13DFA8130C20298',
loaderId: '439236ADE39978F98C20E8939A32D3A5' }
>>> { timestamp: 7454.721299 } // from Page.loadEventFired
>>> Runtime.evaluate({expression: 'window.location.toString()'})
{ result: { type: 'string', value: 'https://github.com/' } }
Additionally there are some custom commands available:
>>> .help
[...]
.reset Remove all the registered event handlers
.target Display the current target
In both the REPL and the regular API every object of the protocol is decorated
with the meta information found within the descriptor. In addition The
category
field is added, which determines if the member is a command
, an
event
or a type
.
For example to learn how to call Page.navigate
:
>>> Page.navigate
{ [Function]
category: 'command',
parameters: { url: { type: 'string', description: 'URL to navigate the page to.' } },
returns:
[ { name: 'frameId',
'$ref': 'FrameId',
hidden: true,
description: 'Frame id that will be navigated.' } ],
description: 'Navigates current page to the given URL.',
handlers: [ 'browser', 'renderer' ] }
To learn about the parameters returned by the Network.requestWillBeSent
event:
>>> Network.requestWillBeSent
{ [Function]
category: 'event',
description: 'Fired when page is about to send HTTP request.',
parameters:
{ requestId: { '$ref': 'RequestId', description: 'Request identifier.' },
frameId:
{ '$ref': 'Page.FrameId',
description: 'Frame identifier.',
hidden: true },
loaderId: { '$ref': 'LoaderId', description: 'Loader identifier.' },
documentURL:
{ type: 'string',
description: 'URL of the document this request is loaded for.' },
request: { '$ref': 'Request', description: 'Request data.' },
timestamp: { '$ref': 'Timestamp', description: 'Timestamp.' },
wallTime:
{ '$ref': 'Timestamp',
hidden: true,
description: 'UTC Timestamp.' },
initiator: { '$ref': 'Initiator', description: 'Request initiator.' },
redirectResponse:
{ optional: true,
'$ref': 'Response',
description: 'Redirect response data.' },
type:
{ '$ref': 'Page.ResourceType',
optional: true,
hidden: true,
description: 'Type of this resource.' } } }
To inspect the Network.Request
(note that unlike commands and events, types
are named in upper camel case) type:
>>> Network.Request
{ category: 'type',
id: 'Request',
type: 'object',
description: 'HTTP request data.',
properties:
{ url: { type: 'string', description: 'Request URL.' },
method: { type: 'string', description: 'HTTP request method.' },
headers: { '$ref': 'Headers', description: 'HTTP request headers.' },
postData:
{ type: 'string',
optional: true,
description: 'HTTP POST request data.' },
mixedContentType:
{ optional: true,
type: 'string',
enum: [Object],
description: 'The mixed content status of the request, as defined in http://www.w3.org/TR/mixed-content/' },
initialPriority:
{ '$ref': 'ResourcePriority',
description: 'Priority of the resource request at the time request is sent.' } } }
By default chrome-remote-interface
asks the remote instance to provide its
own protocol.
This behavior can be changed by setting the local
option to true
upon connection, in which case the local version of
the protocol descriptor is used. This file is manually updated from time to time
using scripts/update-protocol.sh
and pushed to this repository.
To further override the above behavior there are basically two options:
-
pass a custom protocol descriptor upon connection (
protocol
option); -
use the raw version of the commands and events interface to use bleeding-edge features that do not appear in the local version of the protocol descriptor;
This module is able to run within a web context, with obvious limitations
though, namely external HTTP requests
(List, New, etc.) cannot
be performed directly, for this reason the user must provide a global
criRequest
in order to use them:
function criRequest(options, callback) {}
options
is the same object used by the Node.js http
module and callback
is
a function taking two arguments: err
(JavaScript Error
object or null
) and
data
(string result).
Using webpack
It just works, simply require this module:
const CDP = require('chrome-remote-interface');
To generate a JavaScript file that can be used with a <script>
element:
-
run
npm install
from the root directory; -
manually run webpack with:
TARGET=var npm run webpack
-
use as:
<script> function criRequest(options, callback) { /*...*/ } </script> <script src="chrome-remote-interface.js"></script>
The API consists of three parts:
-
DevTools methods (for those implementations that support them, e.g., List, New, etc.);
-
connection establishment;
-
the actual protocol interaction.
Connects to a remote instance using the Chrome Debugging Protocol.
options
is an object with the following optional properties:
-
host
: HTTP frontend host. Defaults tolocalhost
; -
port
: HTTP frontend port. Defaults to9222
; -
secure
: HTTPS/WSS frontend. Defaults tofalse
; -
useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
; -
alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function; -
target
: determines which target this client should attach to. The behavior changes according to the type:- a
function
that takes the array returned by theList
method and returns a target or its numeric index relative to the array; - a target
object
like those returned by theNew
andList
methods; - a
string
representing the raw WebSocket URL, in this casehost
andport
are not used to fetch the target list, yet they are used to complete the URL if relative; - a
string
representing the target id.
Defaults to a function which returns the first available target according to the implementation (note that at most one connection can be established to the same target);
- a
-
protocol
: Chrome Debugging Protocol descriptor object. Defaults to use the protocol chosen according to thelocal
option; -
local
: a boolean indicating whether the protocol must be fetched remotely or if the local version must be used. It has no effect if theprotocol
option is set. Defaults tofalse
.
These options are also valid properties of all the instances of the CDP
class. In addition to that, the webSocketUrl
field contains the currently used
WebSocket URL.
callback
is a listener automatically added to the connect
event of the
returned EventEmitter
. When callback
is omitted a Promise
object is
returned which becomes fulfilled if the connect
event is triggered and
rejected if the error
event is triggered.
The EventEmitter
supports the following events:
function (client) {}
Emitted when the connection to the WebSocket is established.
client
is an instance of the CDP
class.
function (err) {}
Emitted when http://host:port/json
cannot be reached or if it is not possible
to connect to the WebSocket.
err
is an instance of Error
.
Fetch the Chrome Debugging Protocol descriptor.
options
is an object with the following optional properties:
host
: HTTP frontend host. Defaults tolocalhost
;port
: HTTP frontend port. Defaults to9222
;secure
: HTTPS/WSS frontend. Defaults tofalse
;useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
;alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function;local
: a boolean indicating whether the protocol must be fetched remotely or if the local version must be returned. Defaults tofalse
.
callback
is executed when the protocol is fetched, it gets the following
arguments:
err
: aError
object indicating the success status;protocol
: the Chrome Debugging Protocol descriptor.
When callback
is omitted a Promise
object is returned.
For example:
const CDP = require('chrome-remote-interface');
CDP.Protocol((err, protocol) => {
if (!err) {
console.log(JSON.stringify(protocol, null, 4));
}
});
Request the list of the available open targets/tabs of the remote instance.
options
is an object with the following optional properties:
host
: HTTP frontend host. Defaults tolocalhost
;port
: HTTP frontend port. Defaults to9222
;secure
: HTTPS/WSS frontend. Defaults tofalse
;useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
;alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function.
callback
is executed when the list is correctly received, it gets the
following arguments:
err
: aError
object indicating the success status;targets
: the array returned byhttp://host:port/json/list
containing the target list.
When callback
is omitted a Promise
object is returned.
For example:
const CDP = require('chrome-remote-interface');
CDP.List((err, targets) => {
if (!err) {
console.log(targets);
}
});
Create a new target/tab in the remote instance.
options
is an object with the following optional properties:
host
: HTTP frontend host. Defaults tolocalhost
;port
: HTTP frontend port. Defaults to9222
;secure
: HTTPS/WSS frontend. Defaults tofalse
;useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
;alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function;url
: URL to load in the new target/tab. Defaults toabout:blank
.
callback
is executed when the target is created, it gets the following
arguments:
err
: aError
object indicating the success status;target
: the object returned byhttp://host:port/json/new
containing the target.
When callback
is omitted a Promise
object is returned.
For example:
const CDP = require('chrome-remote-interface');
CDP.New((err, target) => {
if (!err) {
console.log(target);
}
});
Activate an open target/tab of the remote instance.
options
is an object with the following properties:
host
: HTTP frontend host. Defaults tolocalhost
;port
: HTTP frontend port. Defaults to9222
;secure
: HTTPS/WSS frontend. Defaults tofalse
;useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
;alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function;id
: Target id. Required, no default.
callback
is executed when the response to the activation request is
received. It gets the following arguments:
err
: aError
object indicating the success status;
When callback
is omitted a Promise
object is returned.
For example:
const CDP = require('chrome-remote-interface');
CDP.Activate({id: 'CC46FBFA-3BDA-493B-B2E4-2BE6EB0D97EC'}, (err) => {
if (!err) {
console.log('target is activated');
}
});
Close an open target/tab of the remote instance.
options
is an object with the following properties:
host
: HTTP frontend host. Defaults tolocalhost
;port
: HTTP frontend port. Defaults to9222
;secure
: HTTPS/WSS frontend. Defaults tofalse
;useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
;alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function;id
: Target id. Required, no default.
callback
is executed when the response to the close request is received. It
gets the following arguments:
err
: aError
object indicating the success status;
When callback
is omitted a Promise
object is returned.
For example:
const CDP = require('chrome-remote-interface');
CDP.Close({id: 'CC46FBFA-3BDA-493B-B2E4-2BE6EB0D97EC'}, (err) => {
if (!err) {
console.log('target is closing');
}
});
Note that the callback is fired when the target is queued for removal, but the actual removal will occur asynchronously.
Request version information from the remote instance.
options
is an object with the following optional properties:
host
: HTTP frontend host. Defaults tolocalhost
;port
: HTTP frontend port. Defaults to9222
;secure
: HTTPS/WSS frontend. Defaults tofalse
;useHostName
: do not perform a DNS lookup of the host. Defaults tofalse
;alterPath
: afunction
taking and returning the path fragment of a URL before that a request happens. Defaults to the identity function.
callback
is executed when the version information is correctly received, it
gets the following arguments:
err
: aError
object indicating the success status;info
: a JSON object returned byhttp://host:port/json/version
containing the version information.
When callback
is omitted a Promise
object is returned.
For example:
const CDP = require('chrome-remote-interface');
CDP.Version((err, info) => {
if (!err) {
console.log(info);
}
});
function (message) {}
Emitted when the remote instance sends any notification through the WebSocket.
message
is the object received, it has the following properties:
method
: a string describing the notification (e.g.,'Network.requestWillBeSent'
);params
: an object containing the payload;sessionId
: an optional string representing the session identifier.
Refer to the Chrome Debugging Protocol specification for more information.
For example:
client.on('event', (message) => {
if (message.method === 'Network.requestWillBeSent') {
console.log(message.params);
}
});
function (params, sessionId) {}
Emitted when the remote instance sends a notification for <domain>.<method>
through the WebSocket.
params
is an object containing the payload.
sessionId
is an optional string representing the session identifier.
This is just a utility event which allows to easily listen for specific
notifications (see 'event'
), for example:
client.on('Network.requestWillBeSent', console.log);
Additionally, the equivalent <domain>.on('<method>', ...)
syntax is available, for example:
client.Network.on('requestWillBeSent', console.log);
function (params, sessionId) {}
Equivalent to the following but only for those events belonging to the given session
:
client.on('<domain>.<event>', callback);
function () {}
Emitted every time that there are no more pending commands waiting for a
response from the remote instance. The interaction is asynchronous so the only
way to serialize a sequence of commands is to use the callback provided by
the send
method. This event acts as a
barrier and it is useful to avoid the callback hell in certain simple
situations.
Users are encouraged to extensively check the response of each method and should prefer the promises API when dealing with complex asynchronous program flows.
For example to load a URL only after having enabled the notifications of both
Network
and Page
domains:
client.Network.enable();
client.Page.enable();
client.once('ready', () => {
client.Page.navigate({url: 'https://github.com'});
});
In this particular case, not enforcing this kind of serialization may cause that the remote instance does not properly deliver the desired notifications the client.
function () {}
Emitted when the instance closes the WebSocket connection.
This may happen for example when the user opens DevTools or when the tab is closed.
Issue a command to the remote instance.
method
is a string describing the command.
params
is an object containing the payload.
sessionId
is a string representing the session identifier.
callback
is executed when the remote instance sends a response to this
command, it gets the following arguments:
error
: a boolean value indicating the success status, as reported by the remote instance;response
: an object containing either the response (result
field, iferror === false
) or the indication of the error (error
field, iferror === true
).
When callback
is omitted a Promise
object is returned instead, with the
fulfilled/rejected states implemented according to the error
parameter. The
Error
object returned contains two additional parameters: request
and
response
which contain the raw massages, useful for debugging purposes. In
case of low-level WebSocket errors, the error
parameter contains the
originating Error
object and no response
is returned.
Note that the field id
mentioned in the Chrome Debugging Protocol
specification is managed internally and it is not exposed to the user.
For example:
client.send('Page.navigate', {url: 'https://github.com'}, console.log);
Just a shorthand for:
client.send('<domain>.<method>', params, sessionId, callback);
For example:
client.Page.navigate({url: 'https://github.com'}, console.log);
Just a shorthand for:
client.on('<domain>.<event>[.<sessionId>]', callback);
When callback
is omitted the event is registered only once and a Promise
object is returned. Notice though that in this case the optional sessionId
usually passed to callback
is not returned.
When callback
is provided, it returns a function that can be used to
unsubscribe callback
from the event, it can be useful when anonymous functions
are used as callbacks.
For example:
const unsubscribe = client.Network.requestWillBeSent((params, sessionId) => {
console.log(params.request.url);
});
unsubscribe();
Close the connection to the remote instance.
callback
is executed when the WebSocket is successfully closed.
When callback
is omitted a Promise
object is returned.
Just a shorthand for:
client.<domain>.<name>
Where <name>
can be a command, an event, or a type.
This means that the Chrome version that you are using does not support
Domain.method
. The solution is to update to a newer version.
See here for more information.
This means that you are providing a custom protocol descriptor
(CDP({protocol: customProtocol})
) which declares Domain.method
while the
Chrome version that you are using does not support it.
To inspect the currently available protocol descriptor use:
$ chrome-remote-interface inspect
See here for more information.
This happens because the size of /dev/shm
is set to 64MB by default in Docker
and may not be enough for Chrome to navigate certain web pages.
You can change this value by running your container with, say,
--shm-size=256m
.
This is thrown by Runtime.evaluate
when the browser-side promise gets
collected by the Chrome's garbage collector, this happens when the whole
JavaScript execution environment is invalidated, e.g., a when page is navigated
or reloaded while a promise is still waiting to be resolved.
Here is an example:
$ chrome-remote-interface inspect
>>> Runtime.evaluate({expression: `new Promise(() => {})`, awaitPromise: true})
>>> Page.reload() // then wait several seconds
{ result: {} }
{ error: { code: -32000, message: 'Promise was collected' } }
To fix this, just make sure there are no pending promises before closing, reloading, etc. a page.
Puppeteer is an additional high-level API built upon the Chrome Debugging Protocol which, among the other things, may start and use a bundled version of Chromium instead of the one installed on your system. Use it if its API meets your needs as it would probably be easier to work with.
chrome-remote-interface instead is just a general purpose 1:1 Node.js binding for the Chrome Debugging Protocol. Use it if you need all the power of the raw protocol, e.g., to implement your own high-level API.
See #240 for a more thorough discussion.