Firefox remote debugging client


firefox-client is a node library for remote debugging Firefox. You can use it to make things like fxconsole, a remote JavaScript REPL.

var FirefoxClient = require("firefox-client");
var client = new FirefoxClient();
client.connect(6000, function() {
  client.listTabs(function(errtabs) {
    console.log("first tab:", tabs[0].url);

With node.js npm package manager:

npm install firefox-client
  1. Enable remote debugging (You'll only have to do this once)

  2. Open the DevTools. Web Developer > Toggle Tools

  3. Visit the settings panel (gear icon)

  4. Check "Enable remote debugging" under Advanced Settings

  5. Listen for a connection

  6. Open the Firefox command line with Tools > Web Developer > Developer Toolbar.

  7. Start a server by entering this command: listen 6000 (where 6000 is the port number)

Follow the instructions in this Hacks video

A limited set of the API (Console, StyleSheets) is compatible with the Simulator 4.0. See the wiki instructions for connecting.

client.listTabs() will list the currently open apps in the Simulator.

client.getWebapps() will expose the webapps in the Simulator, where each app implements the Tab API.

client.getWebapps(function(err, webapps) {
  webapps.getApp("app://", function (err, app) {
    console.log("homescreen:", actor.url);
    app.Console.evaluateJS("alert('foo')", function(err, resp) {
      console.log("alert dismissed");

This latest version of the library will stay compatible with Firefox Nightly. Almost all of it will be compatible with Firefox Aurora as well.

A FirefoxClient is the entry point to the API. After connecting, get a Tab object with listTabs() or selectedTab(). Once you have a Tab, you can call methods and listen to events from the tab's modules, Console or Network. There are also experimental DOM and StyleSheets tab modules, and an upcoming Debugger module.

Almost all API calls take a callback that will get called with an error as the first argument (or null if there is no error), and a return value as the second:

tab.Console.evaluateJS("6 + 7", function(errresp) {
  if (err) throw err;

The modules are EventEmitters, listen for events with on or once, and stop listening with off:

tab.Console.on("page-error", function(event) {
  console.log("new error from tab:", event.errorMessage);

Summary of the offerings of the modules and objects:


Methods: connect(), disconnect(), listTabs(), selectedTab(), getWebapps(), getRoot()

Events: "error", "timeout", "end"


Properties: url, title

Methods: reload(), navigateTo(), attach(), detach()

Events: "navigate", "before-navigate"


Methods: evaluateJS(), startListening(), stopListening(), getCachedLogs()

Events: "page-error", "console-api-call"


Properties: class, name, displayName

Methods: ownPropertyNames(), ownPropertyDescriptor(), ownProperties(), prototype()


Methods: startLogging(), stopLogging(), sendHTTPRequest()

Events: "network-event"


Properties: url, method, isXHR

Methods: getRequestHeaders(), getRequestCookies(), getRequestPostData(), getResponseHeaders(), getResponseCookies(), getResponseContent(), getEventTimings()

Events: "request-headers", "request-cookies", "request-postdata", "response-start", "response-headers", "response-cookies", "event-timings"


Methods: document(), documentElement(), querySelector(), querySelectorAll()


Properties: nodeValue, nodeName, namespaceURI

Methods: parentNode(), parents(), siblings(), nextSibling(), previousSibling(), querySelector(), querySelectorAll(), innerHTML(), outerHTML(), setAttribute(), remove(), release()


Methods: getStyleSheets(), addStyleSheet()


Properties: href, disabled, ruleCount

Methods: getText(), update(), toggleDisabled(), getOriginalSources()

Events: "disabled-changed", "ruleCount-changed"

Methods: measure()

Methods: listRunningApps(), getInstalledApps(), watchApps(), unwatchApps(), launch(), close(), getApp(), installHosted(), installPackaged(), installPackagedWithADB(), uninstall()

Events: "appOpen", "appClose", "appInstall", "appUninstall"

fxconsole - a remote JavaScript console for Firefox

webapps test script - a sample usage of all webapps features

What do you need from the API? File an issue.