Firefox 72 release notes for developers

Changes for web developers

Developer tools

Console:

• In the multi-line mode of the interactive JS interpreter, you can open and save files using the keyboard shortcuts Ctrl + O and Ctrl + S, respectively (Firefox bug 1592308).
• You can set a preference so that asynchronous messages are visually separated (Firefox bug 1592969).

JavaScript debugger:

• You can now right/Ctrl click on objects in the Scopes panel, and choose Property set or Property get to set watchpoints (Firefox bug 1574192).

Network Monitor:

• The Timings tab now shows queued, started, and downloaded times for each resource (Firefox bug 1580431).

Page Inspector:

• You can set a preference to enable a simulator for different values of the prefers-color-scheme media feature (Firefox bug 1550804).

Removals

• The Scratchpad feature has been removed (Firefox bug 1519103).

HTML

No changes.

CSS

• CSS Shadow Parts are now enabled. This includes the part attribute and ::part pseudo-element, which allow shadow hosts to selectively expose chosen elements from their shadow tree to the outside page for styling purposes (Firefox bug 1559074).

• CSS Motion Path has been shipped (Firefox bug 1582554, also see the Intent to Ship). This includes:

  • offset
  • offset-path
  • offset-anchor
  • offset-distance
  • offset-rotate

• The individual transform properties — scale, rotate, and translate — are now enabled by default (Firefox bug 1424900).

Removals

SVG

No changes.

JavaScript

• The nullish coalescing operator has been implemented (Firefox bug 1566141).

APIs

New APIs

• FormDataEvent and event-based form participation is now enabled by default (Firefox bug 1594708).
• The Window.crossOriginIsolated property and the WorkerGlobalScope.crossOriginIsolated property is now supported (Firefox bug 1591892).

DOM

• The Geolocation API has had some interface name updates, as per recent spec changes (Firefox bug 1575144):

  • Coordinates has been changed to GeolocationCoordinates.
  • Position has been changed to GeolocationPosition.
  • PositionError has been changed to GeolocationPositionError.

• A number of properties have been updated to use standard stringifiers (Firefox bug 824857):

  • DOMTokenList.value
  • HTMLAnchorElement.href
  • Location.href
  • MediaList.mediaText
  • URL.href
  • WorkerLocation.href

DOM events

• Notification.requestPermission() and PushManager.subscribe() can now only be called in response to a user gesture such as a click event (Firefox bug 1593644).

Media, Web Audio, and WebRTC

• The MediaDevices.getDisplayMedia() method can now only be called in response to a user gesture such as a click event (Firefox bug 1580944).
• The RTCRtpContributingSource dictionary can now include the rtpTimestamp property, which is a source-generated time at which the packet's media was generated or sampled (Firefox bug 1583867).

Removals

• Removed the non-standard window.mozPaintCount property. (Firefox bug 1591968)
• The BatteryManager interface is no longer exposed to web content (Firefox bug 1441976).
• Navigator.vibrate() is no longer supported in cross-origin <iframe>s (Firefox bug 1591113).
• WebRTC no longer supports the rid= and pt= parameters on the simulcast attribute. The new syntax for a line such as a=simulcast: send rid=7 recv rid=8 is now a=simulcast: send 7 recv 8. The new syntax has been supported since Firefox 68, so now it's time tor retire support for the old syntax (Firefox bug 1470568).

Security

• Opting-out of MIME sniffing using X-Content-Type-Options is now also applied to top-level documents if a Content-type is provided. This can cause HTML web pages to be downloaded instead of being rendered when they are served with a MIME type other than text/html. Make sure to set both headers correctly. (Firefox bug 1591932).
• Dropped the support for HTTP Public Key Pinning (HPKP) because of the low adoption rate and interoperability risk. The Public-Key-Pins and Public-Key-Pins-Report-Only headers are now silently ignored Firefox bug 1412438.

Plugins

No changes.

WebDriver conformance (Marionette)

• Removed Anon and AnonAttribute strategies from WebDriver:FindElement and WebDriver:FindElements commands (Firefox bug 1587627).
• Webdriver:TakeScreenshot no longer fails if captured area exceeds upper maximum bound for the canvas width, height, or size (Firefox bug 1590064).

Changes for add-on developers

API changes

• The browserSettings.ftpProtocolEnabled property has been implemented (Firefox bug 1592687).
• The BrowserSetting.onChange event has been implemented (Firefox bug 1410412).
• The captivePortal.canonicalURL property has been implemented (Firefox bug 1592932).
• The callback functions for the browserAction.onClicked and pageAction.onClicked events now include a OnClickData property containing an object whose properties describe the mouse button pressed along with any keyboard modifiers (Firefox bug 1405031). This allows support for additional types of mouse click.
• The browserSettings.tlsVersionRestrictionConfig property has been implemented and enables the highest and lowest versions of TLS supported by the browser to be read (Firefox bug 1593635).

Manifest changes

No changes.

See also

• Hacks release post: Firefox 72 — our first song of 2020