chrome-remote-interface

Remote Debugging Protocol interface that helps to instrument Chrome by providing a simple abstraction of the two main objects exposed by the protocol in a Node.js fashion: commands and notifications.

chrome-remote-interface is listed among third-party Chrome debugging protocol clients.

This module should work with every browser/adapter implementing the Chrome Remote Debugging Protocol. In particular, it has been tested with:

• Google Chrome (native support);
• Microsoft Edge (via Edge Diagnostics Adapter).

Installation

npm install chrome-remote-interface

Chrome setup

Chrome needs to be started with the --remote-debugging-port=<port> option to enable the Remote Debugging Protocol, for example:

google-chrome --remote-debugging-port=9222

Sample API usage

The following snippet loads https://github.com and dumps every request made.

var Chrome = require('chrome-remote-interface');
Chrome(function (chrome) {
    with (chrome) {
        Network.requestWillBeSent(function (params) {
            console.log(params.request.url);
        });
        Page.loadEventFired(close);
        Network.enable();
        Page.enable();
        once('ready', function () {
            Page.navigate({'url': 'https://github.com'});
        });
    }
}).on('error', function (err) {
    console.error('Cannot connect to Chrome:', err);
});

REPL interface and embedded documentation

This module comes with a REPL interface that can be used to interactively control Chrome (run with --help to display the list of available options). It supports command execution and event binding, see the documentation for chrome.<domain>.<method>([params], [callback]) and chrome.<domain>.<event>(callback). Here's a sample session:

chrome> Network.enable()
chrome> Network.requestWillBeSent(console.log)
chrome> Page.navigate({url: 'https://github.com'})

Every object is decorated with the information available through the Remote Debugging Protocol. The category field determines if the member is a command, an event or a type. Remember that this REPL interface provides completion.

For example to learn how to call Page.navigate:

chrome> 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:

chrome> 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:

chrome> 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.' } } }

Remote Debugging Protocol versions

Currently it is not possible to fetch the protocol descriptor (protocol.json) directly from the instrumented Chrome instance (see #10); rather, that file can be fetched from the proper source repository at every connection. By default, the local version is used.

To override the above behavior there are basically three options:

1. update the local copy with make update-protocol;

2. pass a custom protocol descriptor upon connection;

3. use the raw version of the commands and events interface.

API

module([options], [callback])

Connects to a remote instance of Chrome using the Remote Debugging Protocol.

options is an object with the following optional properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222;
• chooseTab: Either a callback or a tab object (i.e. those returned by New and List methods). The callback is used to determine which remote tab attach to, it takes the array returned by the List method and must return the numeric index of a tab. Defaults to a function which returns the currently active tab (function (tabs) { return 0; });
• protocol: Remote Debugging Protocol descriptor object. Defaults to use the protocol chosen according to the remote option;
• remote: a boolean indicating whether the protocol must be fetched remotely or if the local version must be used. It has not effect if the protocol option is set. Defaults to false.

callback is a listener automatically added to the connect event of the returned EventEmitter; when callback is omitted a Promise object is returned.

Returns an EventEmitter that supports the following events:

Event: 'connect'

function (chrome) {}

Emitted when the connection to Chrome is established.

chrome is an instance of the Chrome class.

Event: 'error'

function (err) {}

Emitted if http://host:port/json can't be reached or if it's not possible to connect to Chrome's remote debugging WebSocket.

err is an instance of Error.

module.Protocol([options], [callback])

Fetch the Remote Debugging Protocol descriptor.

options is an object with the following optional properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222;
• remote: a boolean indicating whether the protocol must be fetched remotely or if the local version must be returned. If it is not possible to fulfill the request then the local version is used. Defaults to false.

callback is executed when the protocol is fetched, it gets the following arguments:

• err: a Error object indicating the success status;
• protocol: an object with the following properties:
  • remote: a boolean indicating whether the returned descriptor is the remote version or not (due to user choice or error);
  • descriptor: the Remote Debugging Protocol descriptor.

When callback is omitted a Promise object is returned.

For example:

var Chrome = require('chrome-remote-interface');
Chrome.Protocol(function (err, protocol) {
    if (!err) {
        console.log(JSON.stringify(protocol.descriptor, null, 4));
    }
});

module.List([options], [callback])

Request the list of the available open tabs of the remote Chrome instance.

options is an object with the following optional properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222.

callback is executed when the list is correctly received, it gets the following arguments:

• err: a Error object indicating the success status;
• tabs: the array returned by http://host:port/json/list containing the tab list.

When callback is omitted a Promise object is returned.

For example:

var Chrome = require('chrome-remote-interface');
Chrome.List(function (err, tabs) {
    if (!err) {
        console.log(tabs);
    }
});

module.New([options], [callback])

Create a new tab in the remote Chrome instance.

options is an object with the following optional properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222.
• url: Remote Debugging Protocol url. Defaults to about:blank.

callback is executed when the tab is created, it gets the following arguments:

• err: a Error object indicating the success status;
• tab: the object returned by http://host:port/json/new containing the tab.

When callback is omitted a Promise object is returned.

For example:

var Chrome = require('chrome-remote-interface');
Chrome.New(function (err, tab) {
    if (!err) {
        console.log(tab);
    }
});

module.Activate([options], [callback])

Activate an open tab of the remote Chrome instance.

options is an object with the following properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222.
• id: Remote Debugging Protocol id. Required, no default.

callback is executed when the response to the activation request is received. It gets the following arguments:

• err: a Error object indicating the success status;

When callback is omitted a Promise object is returned.

For example:

var Chrome = require('chrome-remote-interface');
Chrome.Activate({'id': 'CC46FBFA-3BDA-493B-B2E4-2BE6EB0D97EC'}, function (err) {
    if (!err) {
        console.log('success! tab is closing');
    }
});

module.Close([options], [callback])

Close an open tab of the remote Chrome instance.

options is an object with the following properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222.
• id: Remote Debugging Protocol id. Required, no default.

callback is executed when the response to the close request is received. It gets the following arguments:

• err: a Error object indicating the success status;

When callback is omitted a Promise object is returned.

For example:

var Chrome = require('chrome-remote-interface');
Chrome.Close({'id': 'CC46FBFA-3BDA-493B-B2E4-2BE6EB0D97EC'}, function (err) {
    if (!err) {
        console.log('success! tab is closing');
    }
});

Note that the callback is fired when the tab is queued for removal, but the actual removal will occur asynchronously. It typically takes ~200ms for this to occur.

module.Version([options], [callback])

Request version information from the remote Chrome instance.

options is an object with the following optional properties:

• host: Remote Debugging Protocol host. Defaults to localhost;
• port: Remote Debugging Protocol port. Defaults to 9222.

callback is executed when the version information is correctly received, it gets the following arguments:

• err: a Error object indicating the success status;
• info: a JSON object returned by http://host:port/json/version containing the version information.

When callback is omitted a Promise object is returned.

For example:

var Chrome = require('chrome-remote-interface');
Chrome.Version(function (err, info) {
    if (!err) {
        console.log(info);
    }
});

Class: Chrome

Event: 'event'

function (message) {}

Emitted when Chrome sends a 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.

Refer to the Remote Debugging Protocol specifications for more information.

For example:

on('event', function (message) {
    if (message.method === 'Network.requestWillBeSent') {
        console.log(message.params);
    }
});

Event: '<method>'

function (params) {}

Emitted when Chrome sends a notification for <method> through the WebSocket.

params is an object containing the payload.

This is just a utility event which allows to easily listen for specific notifications (see the above event), for example:

chrome.on('Network.requestWillBeSent', console.log);

Event: 'ready'

function () {}

Emitted every time that there are no more pending commands waiting for a response from Chrome. Note that the interaction with Chrome is asynchronous so the only way to serialize a sequence of commands is to use the callback provided by the chrome.send method. This event acts as a barrier and it is useful to avoid the callback hell in certain simple situations.

For example to load a URL only after having enabled the notifications of both Network and Page domains:

Network.enable();
Page.enable();
once('ready', function() {
    Page.navigate({'url': 'https://github.com'});
});

In this particular case, not enforcing this kind of serialization may cause that Chrome doesn't properly deliver the desired notifications the client.

chrome.send(method, [params], [callback])

Issue a command to Chrome.

method is a string describing the command.

params is an object containing the payload.

callback is executed when Chrome sends a response to this command, it gets the following arguments:

• error: a boolean value indicating the success status, as reported by Chrome;
• response: an object containing either the response sent from Chrome (result field, if error === false) or the indication of the error (error field, if error === true).

When callback is omitted a Promise object is returned instead, with the fulfilled/rejected states implemented according to the error parameter.

Note that the field id mentioned in the Remote Debugging Protocol specifications is managed internally and it's not exposed to the user.

For example:

chrome.send('Page.navigate', {'url': 'https://github.com'}, console.log);

chrome.<domain>.<method>([params], [callback])

Just a shorthand for:

chrome.send('<domain>.<method>', params, callback);

For example:

chrome.Page.navigate({'url': 'https://github.com'}, console.log);

chrome.<domain>.<event>(callback)

Just a shorthand for:

chrome.on('<domain>.<event>', callback);

For example:

chrome.Network.requestWillBeSent(console.log);

chrome.close([callback])

Close the connection to Chrome.

callback is executed when the WebSocket is successfully closed.

When callback is omitted a Promise object is returned.

Contributors

• Andrey Sidorov
• Greg Cochard

Resources

• Chrome Debugger Protocol Viewer
• Chrome Developer Tools: Remote Debugging Protocol v1.1
• Showcase Chrome Debugging Protocol Clients