Firefox 62 for developers

This article provides information about the changes in Firefox 62 that will affect developers. Firefox 62 was released on September 5, 2018.

Changes for web developers

Developer tools

• The Shape Path Editor is now available by default — see Edit Shape Paths in CSS for more information.
• You can now split the Rules view out into its own pane, separate from the other tabs on the CSS pane. See Page inspector 3-pane mode for more details.
• The Grid inspector has updated features, and all new documentation — see CSS Grid Inspector: Examine grid layouts.
• 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 (bug 1192642).
• 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 (bug 1456069).
• The Network Monitor's Cookies tab now shows the cookie samesite attribute (bug 1452715).
• Responsive design mode now works inside container tabs (bug 1306975).
• When CORS errors occur and are reported on the console, Firefox now provides a link to the corresponding page in our CORS error documentation (bug 1475391).
• Create a screenshot of the current page (with an optional filename) from the Console tab (bug 1464461) using the following command:
  
  :screenshot <filename.png> --fullpage
  
  where <filename.png> is the desired filename. The file will be saved to your downloads folder. The --fullpage parameter is optional, but if included, it will save the full web page. This option also adds -fullpage to the name of the file. For a list of all options available for this command, enter: :screenshot --help

Removals

• The Developer Toolbar/GCLI (accessed with Shift + F2), has been removed from Firefox (bug 1461970). 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 unsafeSetInnerHTML work, usage numbers are very low, alternatives exist for the most used commands.

HTML

No changes.

CSS

• :-moz-selection has been unprefixed to ::selection (bug 509958).
• x is now supported as a unit for the <resolution> type (bug 1460655).
• shape-margin, shape-outside, and shape-image-threshold are now enabled by default (bug 1457297).

Removals

• All XUL display values with the exception of -moz-box and -moz-inline-box have been removed from non-XUL documents in bug 1288572.

SVG

No changes.

JavaScript

• The WebAssembly.Global() constructor is now supported, along with global variables in WebAssembly (bug 1464656).
• The Array.prototype.flat() and Array.prototype.flatMap() methods are now enabled by default (bug 1435813).
• The import.meta property has been implemented to expose context-specific metadata to a JavaScript module (bug 1427610).
• 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 (see bug 1435828 and the TC39 proposal json-superset).
• For out-of-bounds typed array indexes, Reflect.defineProperty() and Reflect.set() will now return false instead of true (bug 1308735).

Removals

• The 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 (bug 1186265).
• The URL.createObjectURL() method no longer supports creating object URLs to represent a MediaStream. This capability has been obsolete for some time, since you can now simply set HTMLMediaElement.srcObject to the MediaStream directly (bug 1454889).

APIs

New APIs

• The Speech Synthesis API (Text-to-Speech) is now enabled by default on Firefox for Android (bug 1463496).

DOM

• 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 (bug 1186265).
• For compatibility purposes, the Event.srcElement property is now supported. It is an alias for Event.target (bug 453968).
• Navigator.registerProtocolHandler() now must only be called from a secure context (bug 1460506).
• The Navigator.registerContentHandler() method has been disabled by default in preparation for being removed entirely, as it's been obsolete for some time (bug 1460481).
• The DataTransfer() constructor has been implemented (bug 1351193).
• Document.domain can no longer return null (bug 819475). 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 (bug 1458466).
• Added Console.countReset() to reset a console counter value (bug 1459279).

DOM events

No changes.

Service workers

No changes.

Media, Web Audio, and WebRTC

• The "media.autoplay.enabled" preference now controls automatic playback of both audio and video media, instead of just video media (bug 1413098).
• 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 (bug 1456265).

Removals

• The userproximity and deviceproximity events (see also UserProximityEvent and DeviceProximityEvent) have been disabled by default behind the device.sensors.proximity.enabled preference (bug 1462308).
• The devicelight event (see also DeviceLightEvent) has been disabled by default behind the device.sensors.ambientLight.enabled preference (bug 1462308).
• The DOMSubtreeModified and DOMAttrModified mutation events are no longer thrown when the style attribute is changed via the CSSOM (bug 1460295, see also this site compatibility post).
• Support for CSSStyleDeclaration.getPropertyCSSValue() has been removed (bug 1408301).
• Support for CSSValue, CSSPrimitiveValue, and CSSValueList has been removed (bug 1459871).
• window.getComputedStyle() no longer returns null when called on a Window which has no presentation (bug 1467722).

HTTP

Removals

• The deprecated CSP referrer directive has been removed. Please use the Referrer-Policy header instead (bug 1302449).

Security

No changes.

Plugins

No changes.

WebDriver conformance (Marionette)

New features

• Command WebDriver:ElementSendKeys has been made WebDriver conforming for file uploads (bug 1448792).

• User prompts as raised by beforeunload events are automatically dismissed for WebDriver:Get, WebDriver:Back, WebDriver:Forward, WebDriver:Refresh, and WebDriver:Close commands (bug 1434872).

• WebDriver:PerformActions for Ctrl + Click synthesizes a contextmenu event (bug 1421323).

API changes

• Removed obsolete endpoints including getWindowPosition, setWindowPosition, getWindowSize, and setWindowSize (bug 1348145).
• WebDriver commands which return success with data null now return an empty dictionary (bug 1461463).

Bug fixes

• WebDriver:ExecuteScript caused cyclic reference error for WebElement collections (bug 1447977).

• Dispatching a pointerMove or pause action primitive could cause a hang, and the command to never send a reply (bug 1467743, bug 1447449).

Other

No changes.

Changes for add-on developers

API changes

• Added the webRequest.getSecurityInfo() API to examine details of TLS connections (bug 1322748).
• Added the browserSettings.newTabPosition to customize where new tabs open (bug 1344749).
• windowTypes has been deprecated in windows.get(), windows.getCurrent(), and windows.getLastFocused() (bug 1419132).
• It's now possible to modify a browser action on a per-window basis (bug 1419893).

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 (bug 1460910).
• 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 (bug 1459455).

Removals

• Support for unpacked sideloaded extensions has been removed (bug 1385057).
• The warning about browser_style displayed when temporarily loading an extension for testing is no longer displayed (bug 1404724).

See also

• Site compatibility for Firefox 62

Older versions