Mozilla has a new release for us - Firefox 62 with a whole lot of new features and fixes. We just added it in our cross-browser testing platform. If you don't have Firefox 62 installed you can easily try it out on our machines and you can test your web apps in it as well.

Firefox 62 About Dialog

Try Firefox 62 in Browserling now!

New features in Firefox 62

  • Firefox Home (the default New Tab) now allows users to display up to 4 rows of top sites, Pocket stories, and highlights.
  • “Reopen in Container” tab menu option appears for users with Containers that lets them choose to reopen a tab in a different container.
  • In advance of removing all trust for Symantec-issued certificates in Firefox 63, a preference was added that allows users to distrust certificates issued by Symantec.
  • Added FreeBSD support for WebAuthn.
  • Improved graphics rendering for Windows users without accelerated hardware using Parallel-Off-Main-Thread Painting.
  • Support for CSS Shapes, allowing for richer web page layouts. This goes hand in hand with a brand new Shape Path Editor in the CSS inspector.
  • CSS Variable Fonts (OpenType Font Variations) support, which makes it possible to create beautiful typography with a single font file.
  • Updates for enterprise environments: AutoConfig is sandboxed to the documented API by default.
  • Added Canadian English (en-CA) locale.
  • Removed the description field for bookmarks.
  • Dark theme is automatically enabled in macOS 10.14 dark mode.
  • Changed the default setting to Enforce (3) for the security.pki.name_matching_mode preference.
  • Adobe Flash applets now run in a more secure mode using process sandboxing on macOS.
  • Users disconnecting from Sync are now offered the option to wipe their Firefox profile data (including bookmarks, passwords, history, cookies, and site data) from their desktop computer.
  • Changed how WebRTC handles screen sharing: When screen-sharing a window, the window will be brought to front.
  • Three-pane Inspector in Developer Tools separates the rules into its own panel.
  • Changes affecting developers.

For Android:

  • Improved scrolling performance.
  • Faster page load times over WiFi connections by loading from the network cache if disk cache is slow.
  • “Product and feature tips” toggle in Notifications settings, allowing for more control over which notifications are shown.
  • WebRTC video sessions between Firefox for Android and Safari browsers works again.

Changes in Firefox 62

  • Removed the description field for bookmarks. Users who have stored descriptions using the field may wish to export these descriptions as html or json files, as they will be removed in a future release.
  • Dark theme is automatically enabled in macOS 10.14 dark mode
  • Changed the default setting to Enforce (3) for the security.pki.name_matching_mode preference
  • Adobe Flash applets now run in a more secure mode using process sandboxing on macOS. Learn how this may affect features here.
  • Users disconnecting from Sync are now offered the option to wipe their Firefox profile data (including bookmarks, passwords, history, cookies, and site data) from their desktop computer
  • Changed how WebRTC handles screen sharing: When screen-sharing a window, the window will be brought to front

Unresolved issues in Firefox 62

  • Unvisited bookmarks will not be autofilled in the address bar
  • File management can fail on macOS Mojave (10.14)

Developer Tools Changes in Firefox 62

  • The Shape Path Editor is now available by default.
  • You can now split the Rules view out into its own pane, separate from the other tabs on the CSS pane.
  • The Grid inspector has updated features, and all new documentation.
  • You now have four options for the location of the Developer Tools. In addition to the default location on the bottom of the window, you can choose to locate the tools on either the left or right sides of the main window or in a separate window.
  • The Accessibility Inspector has had a couple of minor updates - it no longer exposes the help property, which isn't properly implemented in Gecko and the keyboardShortcut property now correctly exposes any keyboard shortcut available to activate the currently inspected node.
  • A close button has been added to the split console toolbar.
  • If the option to "Select an iframe as the currently targeted document" is checked, the icon will appear in the toolbar while the Settings tab is displayed, even if the current page doesn't include any iframes.
  • The Network Monitor's Cookies tab now shows the cookie samesite attribute.
  • Responsive design mode now works inside container tabs.
  • When CORS errors occur and are reported on the console, Firefox now provides a link to the corresponding page in our CORS error documentation.
  • You can create a screenshot of the current page (with an optional filename) from the Console tab using the :screenshot command.
  • The Developer Toolbar/GCLI (accessed with Shift + F2) has been removed from Firefox. Both the Developer Toolbar UI and the GCLI upstream library have become unmaintained, some of its features are broken (some ever since e10s), it is blocking the unsafeSetInnerHTMLwork, usage numbers are very low, alternatives exist for the most used commands.

CSS Changes in Firefox 62

  • :-moz-selection has been unprefixed to ::selection.
  • x is now supported as a unit for the <resolution> ) type.
  • shape-margin, shape-outside , and shape-image-threshold are now enabled by default.
  • Removed all XUL display values with the exception of -moz-box and -moz-inline-boxhave been removed from non-XUL documents.

Javascript Changes in Firefox 62

  • The WebAssembly.Global() constructor is now supported, along with global variables in WebAssembly.
  • The Array.prototype.flat() and Array.prototype.flatMap() methods are now enabled by defaul.
  • The import.meta property has been implemented to expose context-specific metadata to a JavaScript module.
  • JavaScript string literals may now directly contain the U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR characters. As a consequence, JSON syntax is now a subset of JavaScript literal syntax.
  • For out-of-bounds typed array indexes, Reflect.defineProperty() and Reflect.set() will now return false instead of true .
  • Removed DOMPoint and DOMPointReadOnly constructors no longer support an input parameter of type DOMPointInit; the values of the properties must be specified using the x, y, z, and w parameters.
  • Removed URL.createObjectURL() method no longer supports creating object URLs to represent a MediaStream. This capability has been obsolete for some time now, since you can now simply set HTMLMediaElement.srcObject to the MediaStream directly.

APIs Changes in Firefox 62

New APIs:

  • The Speech Synthesis API (Text-to-Speech) is now enabled by default on Firefox for Android.

DOM Updates:

  • The DOMPointReadOnly interface now supports the static function DOMPointReadOnly.fromPoint(), which creates a new point object from a dictionary that's compatible with DOMPointInit, which includes any DOMPoint object. This function is also available on DOMPoint.
  • For compatibility purposes, the Event.srcElement property is now supported. It is an alias for
  • Navigator.registerProtocolHandler() now must only be called from a secure context.
  • The Navigator.registerContentHandler() method has been disabled by default in preparation for being removed entirely, as it's been obsolete for some time.
  • The DataTransfer() constructor has been implemented.
  • Document.domain can no longer return null. If the domain cannot be identified, then domain returns an empty string instead of null.
  • Added the Console.timeLog() method to display the current value of a console timer while continuing to track the time.
  • Added Console.countReset() to reset a console counter value.

Media, Web Audio, and WebRTC Updates:

  • The "media.autoplay.enabled" preference now controls automatic playback of both audio and video media, instead of just video media.
  • The ChannelSplitterNode has been fixed to correctly default to having 6 channels with the channelInterpretation set to "discrete" and the channelCountMode set to "explicit", as per the specification.

API Removals:

  • The userproximity and deviceproximity events have been disabled by default behind the device.sensors.proximity.enabled preference.
  • The devicelight event has been disabled by default behind the device.sensors.ambientLight.enabled preference.
  • The DOMSubtreeModified and DOMAttrModified mutation events are no longer thrown when the style attribute is changed via the CSSOM.
  • Support for CSSStyleDeclaration.getPropertyCSSValue() has been removed.
  • Support for CSSValue, CSSPrimitiveValue, and CSSValueList has been removed.
  • window.getComputedStyle() no longer returns null when called on a Windowwhich has no presentation.

HTTP Changes in Firefox 62

  • The deprecated CSP referrer directive has been removed. Please use the Referrer-Policy header instead.

WebDriver conformance (Marionette)

New features

  • Command "WebDriver:ElementSendKeys" has been made WebDriver conforming for file uploads.
  • User prompts as raised by "beforeunload" events are automatically dismissed for "WebDriver:Get", "WebDriver:Back", "WebDriver:Forward", "WebDriver:Refresh", and "WebDriver:Close" commands.
  • "WebDriver:PerformActions" for Ctrl + Click synthesizes a contextmenuevent.
  • Removed obsolete endpoints including "getWindowPosition", "setWindowPosition", "getWindowSize", and "setWindowSize".
  • WebDriver commands which return success with data "null" now return an empty dictionary.
  • "WebDriver:ExecuteScript" caused cyclic reference error for WebElement collections.
  • Dispatching a "pointerMove" or "pause" action primitive could cause a hang, and the command to never send a reply.

Add-on Developers Changes in Firefox 62

  • Added the webRequest.getSecurityInfo() API to examine details of TLS connections.
  • Added the browserSettings.newTabPosition to customize where new tabs open.
  • windowTypes has been deprecated in windows.get(), windows.getCurrent(), and windows.getLastFocused().
  • It's now possible to modify a browser action on a per-window basis.

Manifest changes:

  • New open_at_install property of the sidebar_action manifest key enables extensions to control whether their sidebars should open automatically on install or not.
  • Changes to the browser_style property of various manifest keys:
    • In page_action and browser_action it defaults to false.
    • In sidebar_action and options_ui it defaults to true.

Theme changes:

  • New tab_background_separator property of the theme manifest key enables extensions to change the color of the tab separator.


  • Support for unpacked sideloaded extensions has been removed.
  • The warning about browser_style displayed when temporarily loading an extension for testing is no longer displayed.

Security vulnerabilities fixed in Firefox 62

  • CVE-2018-12377: Use-after-free in refresh driver timers.
  • CVE-2018-12378: Use-after-free in IndexedDB.
  • CVE-2018-12379: Out-of-bounds write with malicious MAR file.
  • CVE-2017-16541: Proxy bypass using automount and autofs.
  • CVE-2018-12381: Dragging and dropping Outlook email message results in page navigation.
  • CVE-2018-12382: Addressbar spoofing with javascript URI on Firefox for Android.
  • CVE-2018-12383: Setting a master password post-Firefox 58 does not delete unencrypted previously stored passwords.
  • CVE-2018-12375: Memory safety bugs fixed in Firefox 62.
  • CVE-2018-12376: Memory safety bugs fixed in Firefox 62 and Firefox ESR 60.2.

Have fun cross-browser testing your apps in Firefox 62 and Browserling!