Firefox 56 for developers
Firefox 56 was released on September 28, 2017. This article lists key changes that are useful for web developers.
- Display Negative Line Numbers in CSS Grid Inspector (bug 1369942).
- The new CSS Grid Layout Panel is now available, allowing much better CSS Grid debugging facilities (bug 1181227). See Powerful New Additions to the CSS Grid Inspector in Firefox Nightly for more details.
- On Mac,
Document.hiddenis now true when the window is behind another non-translucent application bug 1236512.
Gamepad.displayIdproperty has been implemented (bug 1375816).
PerformanceTiming.secureConnectionStartproperty has been implemented (bug 772589).
- Firefox used to accept
iso-2022-jp-2sequences silently when an
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. (bug 715833).
- The 4ms clamping behavior of
setInterval()has been updated to be more in line with other browsers, as described in Timeouts throttled to >=4ms (bug 1378586).
- The Page Visibility API's
Document.onvisibilitychangehandler has been added (bug 1333912).
Window.showModalDialog()method has been removed (bug 981796).
- The implementation of the
HTMLButtonElement.formActionproperties has been updated so that they return the correct form submission URL, as per spec (bug 1366361).
Media and WebRTC
- Firefox now supports the
RTCPeerConnectionproperties which let you examine the current and pending configurations of the local and remote ends of the connection, to help manage changes in configuration:
- Hardware encoding of media is now enabled by default on Android; it was available but disabled by default in Firefox 55 (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
CanvasRenderingContext2D.drawImage()method has been updated so that smoothing occurs when downscaling even if
false. This is not mandatory as per spec, but follows Chrome's behavior. See bug 1360415.
SVGImageElementcan now be used as a
CanvasImageSource, e.g. as the image source in a
drawImage()call (bug 1382027).
- Firefox for Android has removed all support for plugins (bug 1381916).
- browsingData.RemovalOptions gets "hostnames" option for cookies
- browsingData.settings() and browsingData.removeCookies() are now supported on Firefox for Android
- browser_style usage is changed
- contextMenus renamed to menus
- cookies.set() and cookies.remove() now work in private browsing mode
- downloads.open() can now only be called from a user action
- FindProxyForURL "DIRECT" return type no longer takes an argument
- history.onVisited now includes the page title if it is known.
- management.get() and management.getAll()
- menus now supports the "tools_menu" context
- menus.OnClickData now has "linkText"
- menus.create() now has an "icons" option
- pageAction.show() and pageAction.hide() are now supported on Firefox for Android
- permissions now supports "unlimitedStorage"
- privacy.services now includes passwordSavingEnabled
- protocol_handlers now supports "gopher"
- proxy.registerProxyScript() is renamed to proxy.register()
- runtime.onInstalled gets
- tabs.print(), tabs.PageSettings, tabs.printPreview(), tabs.saveAsPDF()
- windows.create() and windows.update() now support prefacing window title
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