Firefox 73 release notes for developers

This article provides information about the changes in Firefox 73 that will affect developers. Firefox 73 was released on February 11, 2020.

Changes for web developers

Developer tools

• CORS errors now appear as errors in the console (and no longer as warnings) giving them the appropriate visibility (Firefox bug 1602093).
• Text and regular expression searches in the web console can now be negated by prefixing them with '-' (Firefox bug 1291192).

HTML

No changes.

CSS

• We've implemented {{cssxref("overscroll-behavior-block")}} and {{cssxref("overscroll-behavior-inline")}}, the logical mappings for {{cssxref("overscroll-behavior-x")}} and {{cssxref("overscroll-behavior-y")}} (Firefox bug 833953).

Removals

• The proprietary -moz-touch-enabled media query has been removed (Firefox bug 1486964). You should use pointer: coarse instead.

SVG

• The {{SVGAttr("letter-spacing")}} and {{SVGAttr("word-spacing")}} properties now work in SVG (Firefox bug 371787).

MathML

Removals

• The deprecated {{MathMLElement("mfenced")}} element has been removed (Firefox bug 1603773). Use the {{MathMLElement("mrow")}} and {{MathMLElement("mo")}} elements instead.

JavaScript

• The yearName and relatedYear fields have been made available in the DateTimeFormat.prototype.formatToParts() method, enabling useful formatting options for CJK calendars (Firefox bug 1591664).

APIs

DOM

• The {{domxref("Window.innerWidth", "innerWidth")}} and {{domxref("Window.innerHeight", "innerHeight")}} properties on {{domxref("Window")}} objects have been updated to return the width and height of the layout viewport in all situations, rather than sometimes being based on the visual viewport. In particular, previously when using Responsive Design Mode, these returned the visual viewport dimensions, causing the behavior to vary from what was expected (Firefox bug 1514429).

WebVR

• The deprecated WebVR API—which has been supplanted by WebXR, which supports both augmented and virtual reality applications—now requires a secure context using the {{Glossary("HTTPS")}} protocol to operate. This is due to the availability of sensitive input sources that may include private information (Firefox bug 1381645).

Removals

• Support for the {{domxref("VideoPlaybackQuality")}} property {{domxref("VideoPlaybackQuality.corruptedVideoFrames", "corruptedVideoFrames")}}, which has been deprecated in the specification, has been removed from Firefox (Firefox bug 1602163).

Security

No changes.

WebDriver conformance (Marionette)

• Added WebDriver:Print to print the current page as a PDF document (Firefox bug 1604506).
• Webdriver:TakeScreenshot now always captures the top-level browsing context and not the currently-selected browsing context, if no element to capture has been specified (Firefox bug 1398087, Firefox bug 1606794).
• Using Webdriver:TakeScreenshot's full argument causes the complete page to be captured (Firefox bug 1571424).

Changes for add-on developers

API changes

• The {{WebExtAPIRef("sidebarAction.toggle()")}} function has been implemented (bug 1453355).

Manifest changes

No changes.

See also

• Hacks blog post: Firefox 73 is upon us