Firefox 83 for developers

This article provides information about the changes in Firefox 83 that will affect developers. Firefox 83 was released on November 17, 2020.

Changes for web developers

Developer Tools

• When using the :screenshot helper command in the Web Console, the --dpr parameter is no longer ignored when taking a fullscreen screenshot using --fullpage (bug 1645284).
• Developers can use the scroll badge in the Page Inspector to Debug scrollable overflow. Selecting the badge highlights elements that are causing overflow and marks them with the overflow badge (bug 1669129).

HTML/XML

• The crossorigin attribute is now supported for <link rel=icon> (bug 1661075).
• The displaystyle attribute is now implemented for all MathML elements (bug 1666075).

CSS

• The vendor prefixed :-moz-any() is now aliased to the standard :is() CSS pseudo-class function (bug 1666086).
• We've added support for CSS Conic Gradients (bug 1632351) and (bug 1175958).

JavaScript

• Intl[@@toStringTag] has been added, returning a default value of Intl (recent addition to the ECMA spec). (bug 1670053)

HTTP

No changes

APIs

No changes

WebDriver conformance (Marionette)

• We've removed preliminary support for WebDriver:SwitchToShadowRoot, which hasn't been added to the WebDriver specification yet (bug 1662468).
• We fixed a bug in WebDriver:Back and WebDriver:Forward that caused Marionette to hang when the navigation was triggered from within an <iframe> that gets removed (bug 1672758).

Changes for add-on developers

No changes

Older versions