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Firefox 56 release notes for developers

files/en-us/mozilla/firefox/releases/56/index.md

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Firefox 56 was released on September 28, 2017. This article lists key changes that are useful for web developers.

Changes for web developers

Developer Tools

HTML

CSS

  • Implemented the proprietary Mozilla-specific {{cssxref("<color>")}} values -moz-win-accentcolor and -moz-win-accentcolortext (see Firefox bug 1344910), and the proprietary media query -moz-windows-accent-color-in-titlebar (see Firefox bug 1379938).

SVG

No changes.

JavaScript

APIs

New APIs

No changes.

DOM

  • On Mac, {{domxref("Document.hidden")}} is now true when the window is behind another non-translucent application Firefox bug 1236512.
  • The {{domxref("Gamepad.displayId")}} property has been implemented (Firefox bug 1375816).
  • The {{domxref("PerformanceTiming.secureConnectionStart")}} property has been implemented (Firefox bug 772589).
  • Firefox used to accept iso-2022-jp-2 sequences silently when an iso-2022-jp {{domxref("TextDecoder.TextDecoder","TextDecoder()")}} was instantiated, however this has now been removed to simplify the API, as no other browsers support it and no pages seem to use it. (Firefox bug 715833).
  • The 4ms clamping behavior of {{domxref("Window.setTimeout()")}}, {{domxref("WorkerGlobalScope.setTimeout()")}}, {{domxref("Window.setInterval()")}} and {{domxref("WorkerGlobalScope.setInterval()")}} has been updated to be more in line with other browsers, as described in Reasons for longer delays than specified (Firefox bug 1378586).
  • The Page Visibility API's {{domxref("Document.visibilitychange_event", "onvisibilitychange")}} handler has been added (Firefox bug 1333912).
  • The Window.showModalDialog() method has been removed (Firefox bug 981796).
  • The implementation of the {{domxref("HTMLFormElement.action")}}, {{domxref("HTMLInputElement.formAction")}}, and {{domxref("HTMLButtonElement.formAction")}} properties has been updated so that they return the correct form submission URL, as per spec (Firefox bug 1366361).

DOM events

  • {{domxref("Element/wheel_event", "onwheel")}} is now available on {{domxref("HTMLElement")}} — it wasn't before (Firefox bug 1370550).

Media and WebRTC

  • Firefox now supports the {{domxref("RTCPeerConnection")}} properties which let you examine the current and pending configurations of the local and remote ends of the connection, to help manage changes in configuration: {{domxref("RTCPeerConnection.currentLocalDescription", "currentLocalDescription")}}, {{domxref("RTCPeerConnection.pendingLocalDescription", "pendingLocalDescription")}}, {{domxref("RTCPeerConnection.currentRemoteDescription", "currentRemoteDescription")}}, and {{domxref("RTCPeerConnection.pendingRemoteDescription", "pendingRemoteDescription")}}.
  • Hardware encoding of media is now enabled by default on Android; it was available but disabled by default in Firefox 55 (Firefox bug 1386974). This supports higher-efficiency encoding of VP8 media on devices that provide support for it. This saves battery life and processor power, generally improving the performance of the user's device.

Canvas and WebGL

  • The {{domxref("CanvasRenderingContext2D.drawImage()")}} method has been updated so that smoothing occurs when downscaling even if imageSmoothingEnabled is false. This is not mandatory as per spec, but follows Chrome's behavior. See Firefox bug 1360415.
  • An {{domxref("SVGImageElement")}} can now be used as the image source in a {{domxref("CanvasRenderingContext2D.drawImage","drawImage()")}} call (Firefox bug 1382027).

Security

No changes.

Plugins

  • Firefox for Android has removed all support for plugins (bug 1381916).

Other

Removals from the web platform

HTML

APIs

No changes.

SVG

No changes.

Changes for add-on and Mozilla developers

WebExtensions