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Firefox 63 release notes for developers

files/en-us/mozilla/firefox/releases/63/index.md

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This article provides information about the changes in Firefox 63 that will affect developers. Firefox 63 was released on October 23, 2018.

Changes for web developers

Developer tools

HTML

  • Support for the {{HTMLElement("img")}} element's decoding attribute has been added (Firefox bug 1416328); see also {{DOMxRef("HTMLImageElement.decoding")}}.

Removals

  • Support for the sidebar link type (rel="sidebar") has been removed. If an anchor tag includes this attribute, it will be ignored (Firefox bug 1452645).

CSS

Removals

  • Removed offset-block-start, offset-block-end, offset-inline-start, and offset-inline-end; these have been renamed to inset-*, as described above (Firefox bug 1464782).

SVG

No changes.

JavaScript

Removals

  • Experimental WebAssembly Module IndexedDB serialization support has been removed (Firefox bug 1469395).

APIs

New APIs

  • The Shadow DOM (Firefox bug 1471947) and Custom Elements (Firefox bug 1471948) APIs have been enabled by default; see Web components for more details.
  • The {{domxref("Media_Capabilities_API", "Media Capabilities API", "", "1")}} has been implemented (Firefox bug 1409664).
  • The {{domxref("Clipboard", "Async Clipboard API", "", "1")}} has been implemented and enabled by default for all channels (Firefox bug 1461465). As is the case with Chrome, Firefox currently implements only the {{domxref("Clipboard.writeText", "writeText()")}} and {{domxref("Clipboard.readText", "readText()")}} methods; however, unlike Chrome, readText() is only available in browser extensions.
  • The {{DOMxRef("SecurityPolicyViolationEvent")}} interface is now supported. It allows sending events when the {{HTTPHeader("Content-Security-Policy")}} is violated (Firefox bug 1472661).

DOM

  • The following portions of the {{domxref("Web_Animations_API", "Web Animations API", "", "1")}} have been enabled by default (see Firefox bug 1476158):

    • The {{DOMxRef("Animation")}} properties {{DOMxRef("Animation.ready", "ready")}} and {{DOMxRef("Animation.finished", "finished")}}, specifying the Animation object's ready and finished {{JSxRef("Promise")}}s.
    • The {{DOMxRef("Animation")}} object's {{DOMxRef("Animation.effect", "effect")}} property.
    • The interfaces {{DOMxRef("KeyframeEffect")}} and {{DOMxRef("AnimationEffect")}}.

  • The {{DOMxRef("Element.toggleAttribute()")}} method has been implemented (Firefox bug 1469592).

  • The historical, previously non-standard, {{DOMxRef("Event.returnValue")}} property is now supported for compatibility purposes (Firefox bug 1452569).

  • We implemented the {{DOMxRef("Window.event")}} property to improve web compatibility, now that it's become standard (Firefox bug 218415). However, due to some web compat issues (e.g., Firefox bug 1479964), this was quickly disabled in non-Nightly channels, hidden behind the dom.window.event.enabled pref (Firefox bug 1493869).

  • To bring Firefox into alignment with Edge and Chrome, the {{DOMxRef("Navigator/platform", "navigator.platform")}} property now returns "Win32" even when running on 64-bit Windows (Firefox bug 1472618).

  • Prior to Firefox 63, links that open new windows that had rel="noopener", as well as calls to {{DOMxRef("Window.open()")}} with the noopener window feature enabled would default to having all window features disabled so that you had to explicitly re-enable any standard features you wanted. Now, these windows have the same set of features enabled like any other window, and you need to explicitly turn off any you don't want (Firefox bug 1419960).

DOM events

  • Handling of the Alt key on the right side of the keyboard has been improved on Windows. If the user's current keyboard layout maps the Alt key to the AltGr modifier key, the value of {{DOMxRef("KeyboardEvent.key")}} is now reported as "AltGraph". This behavior matches the behavior recently introduced in Chrome (Firefox bug 900750).

Media, Web Audio, and WebRTC

  • Microphone access now works simultaneously in multiple tabs, even within the same content process (Firefox bug 1404977).
  • {{DOMxRef("RTCDataChannel")}} has been updated to support the sctp-sdp-21 data format for the data, in addition to the older sctp-sdp-05 format previously supported.
  • The {{DOMxRef("ConstantSourceNode")}} node type for Web Audio API now has a default channel count of 2 rather than 1, in order to match the specification (Firefox bug 1413283).
  • The {{domxref("Web_Audio_API", "Web Audio API", "", "1")}} interface {{DOMxRef("AudioScheduledSourceNode")}} (and by extension, all the other node types based on it) now throw the correct exception when a negative value is specified for the node start time. That error is RangeError (Firefox bug 1413284).
  • The minimum and maximum permitted values for an {{DOMxRef("AudioParam")}} object's {{DOMxRef("AudioParam.value", "value")}} have been changed to the minimum negative single-precision floating-point value (-340,282,346,638,528,859,811,704,183,484,516,925,440) and the maximum positive single-precision floating-point value (+340,282,346,638,528,859,811,704,183,484,516,925,440) respectively (Firefox bug 1476695).
  • The {{DOMxRef("SourceBuffer.changeType")}} method, which allows you to change codecs during an active stream, has been enabled by default. This is part of the {{domxref("Media_Source_Extensions_API", "Media Source Extensions API", "", "1")}} (Firefox bug 1481166).
  • The {{DOMxRef("AudioParam.setValueCurveAtTime()")}} method has been updated to correctly accept an array of floating-point values to indicate the parameter's values to change to over time. Previously, it required a {{jsxref("Float32Array")}} (Firefox bug 1421091).
  • {{DOMxRef("AudioParam.setValueCurveAtTime()")}} has also been updated to correctly return a proper TypeError when a non-finite value is found in the values array (Firefox bug 1472095).
  • In addition, setValueCurveAtTime() has been updated to ensure that, when the parameter finishes following the specified value curve after the duration elapses, the value of the parameter is set to the last value in the list of values to curve through (Firefox bug 1308436).
  • The RTCRTPStreamStats dictionary has been renamed to RTCRtpStreamStats for consistency with other WebRTC dictionaries and the specification (Firefox bug 1480498).
  • Support for the RTCRtpStreamStats dictionary's kind property has been added (Firefox bug 1481851).
  • The RTCRtpStreamStats dictionary's isRemote property is deprecated and will be removed in Firefox 65. A warning is now output to console when this property is accessed. See this blog post on the Advancing WebRTC blog for details (Firefox bug 1393306).

Canvas and WebGL

  • A new powerPreference context attribute has been added to {{DOMxRef("HTMLCanvasElement.getContext()")}}. On macOS this allows WebGL non-performance-critical applications and applets to request the low-power GPU instead of the high-power GPU in multi-GPU systems (Firefox bug 1349799).

Removals

  • The obsolete and non-standard Firefox-only methods Window.back() and Window.forward() have been removed. Please use the {{DOMxRef("History.back", "window.history.back()")}} and {{DOMxRef("History.forward", "window.history.forward()")}} methods instead (Firefox bug 1479486).
  • The {{domxref("URL.createObjectURL_static", "URL.createObjectURL()")}} and {{DOMxRef("URL.revokeObjectURL_static", "URL.revokeObjectURL()")}} methods are no longer available on {{DOMxRef("ServiceWorker")}} instances due to the potential they introduced for memory leaks to occur (Firefox bug 1264182).
  • Since it was deprecated in the specification anyway, the limited support for Doppler effects on {{DOMxRef("PannerNode")}} has been removed from the Web Audio API. The {{DOMxRef("AudioListener")}} properties dopplerFactor and speedOfSound have been removed, along with the PannerNode method setVelocity() (Firefox bug 1148354).

CSSOM

No changes.

HTTP

  • The {{HTTPHeader("Clear-Site-Data")}} header is implemented and no longer behind a preference (Firefox bug 1470111).

Security

  • Site favicons are now subject to Content Security Policy if one is configured for the site (Firefox bug 1297156).
  • CSP script-src directive's 'report-sample' expression now recognized when generating violation reports. This directive indicates that a short sample of where the violation occurred should be included in the report. Previously, Firefox always included this sample (Firefox bug 1473218).
  • Firefox now uses NSS 3.39 (Firefox bug 1470914).

Plugins

No changes.

WebDriver conformance (Marionette)

New features

  • Marionette now returns a setWindowRect capability in the WebDriver:NewSession response that is true if the browser window can be repositioned and resized, which e.g., is the case for Firefox but not any mobile applications (Firefox bug 1470659).
  • Added support for the unhandledPromptBehavior capability, which allows to define a specific prompt behavior of the WebDriver specification (Firefox bug 1264259).
  • Handling of user prompts has been added to the WebDriver:ExecuteScript and WebDriver:ExecuteAsyncScript commands (Firefox bug 1439995).

API changes

  • Deprecated command end-points without the WebDriver: prefix have been removed (Firefox bug 1451725).
  • The WebDriver:NewSession command returns recommended strings (linux, mac, windows) for platformName as defined in the WebDriver specification (Firefox bug 1470646).

Bug fixes

  • Focus related events were missing on element interaction when Firefox was not running as the top-most application (Firefox bug 1398111).
  • Performing a pointerDown and pointerUp action in a subsequent action sequence could trigger a double click because WebDriver:ReleaseActions didn't reset the double click tracker (Firefox bug 1422583).
  • Executing pause actions repeatedly could cause an infinite hang (Firefox bug 1447449).
  • Fixed a bug where returning an element collection from WebDriver:ExecuteScript and WebDriver:ExecuteAsyncScript would cause a cyclic reference error (Firefox bug 1447977).
  • To prevent a race condition both the WebDriver:AcceptAlert and WebDriver:DismissAlert commands now wait until the user prompt has been closed (Firefox bug 1479368).
  • Log entries as emitted by the frame script were no longer limited by MarionettePrefs.logLevel but logged everything (Firefox bug 1482829).
  • WebDriver:TakeScreenshot raised an error when taking a screenshot of a window larger than 32767 pixels in width or height (Firefox bug 1485730).
  • WebDriver:SendAlertText didn't replace default user prompt value if text to send is an empty string (Firefox bug 1486485).

Other

  • Corrected the behavior of {{DOMxRef("PerformanceObserver.observe()")}} to do nothing if no valid entry types are found in the specified array of entry types to observe, or if the array is empty or missing. Previously, Firefox was incorrectly throwing a TypeError (Firefox bug 1403027).
  • In OpenSearch, Firefox now accepts application/json as a search URL type, as an alias of application/x-suggestions+json (Firefox bug 1425827).

Changes for add-on developers

API changes

Theming

  • The default text color for {{WebExtAPIRef("browserAction")}} badges is now automatically set to black or white, to maximize contrast with the background (Firefox bug 1474110).

  • The accentcolor and textcolor properties of the theme manifest key are now optional (Firefox bug 1413144).

  • {{WebExtAPIRef("browserAction.getBadgeTextColor()")}} and {{WebExtAPIRef("browserAction.setBadgeTextColor()")}} enable you to get and set the text color of browser action badges (Firefox bug 1424620).

  • The theme colors key in manifest.json now supports the ntp_text property to set the text color in a new tab, and the ntp_background property to set the color of a new tab (Firefox bug 1347204).

  • Themes can now define the colors for sidebars, such as the bookmarks sidebar (Firefox bug 1418602). The relevant properties include:

    • sidebar: The background color for sidebars.
    • sidebar_text: The text color for sidebars.
    • sidebar_highlight: The background color of a selected item in a sidebar.
    • sidebar_highlight_text: The text color of a selected item in a sidebar.

  • The method {{WebExtAPIRef("management.install()")}} allows web extensions to install and enable signed browser themes (Firefox bug 1369209).

  • The manifest key theme_experiment was introduced (Firefox bug 1472740). This key enables the definition of experimental theme key properties for the Firefox interface.

Search

  • The new {{WebExtAPIRef("search")}} API enables you to retrieve the list of installed search engines and perform searches with them (Firefox bug 1352598).
  • {{WebExtAPIRef("topSites.get()")}} now takes an options parameter enabling you to set various options for the list of sites returned (Firefox bug 1445836).

Tabs

  • {{WebExtAPIRef("tabs.onHighlighted")}} now supports multi-select (Firefox bug 1474440).
  • {{WebExtAPIRef("tabs.highlight")}} now includes an optional field in the highlightInfo object — populate — which defaults to true. Setting it to false prevents the returned windows.Window object from being populated with a list of tabs, to improve performance (Firefox bug 1489814).
  • {{WebExtAPIRef("tabs.update")}} now supports changing the selection status of a tab by including highlighted: true in the updateProperties parameter (Firefox bug 1479129).
  • {{WebExtAPIRef("tabs.update")}} now supports changing the selection status of a tab without changing the focused tab (Firefox bug 1486050) by including both highlighted: true and active: false in the updateProperties parameter.
  • {{WebExtAPIRef("tabs.query")}} now returns an array of {{WebExtAPIRef("tabs.Tab")}} objects if multiple tabs are selected (Firefox bug 1465170).
  • The {{WebExtAPIRef("tabs.Tab")}} property now properly reflects which tabs in a browser window are selected (highlighted) and {{WebExtAPIRef("tabs.highlight")}} supports changing the highlighted status of multiple tabs (Firefox bug 1464862).
  • The isarticle property in the filter object passed into {{WebExtAPIRef("tabs.onUpdated")}} has been renamed to isArticle. The old name is retained but deprecated. This change was uplifted to Firefox 62 (Firefox bug 1461695).
  • The {{WebExtAPIRef('tabs.onUpdated')}} event can be used to track when a tab is drawing the user's attention with attention property of the changeInfo object (Firefox bug 1396684).

Menus

  • Added {{WebExtApiRef("menus.getTargetElement()")}} to the {{WebExtApiRef("menus")}} API. The method returns the element referenced by the targetElementId parameter that identifies the clicked element. If the targetElementId is no longer valid, the method returns null (Firefox bug 1325814).
  • {{WebExtAPIRef("menus.create()")}} now enables you to create invisible menu items, and {{WebExtAPIRef("menus.update()")}} enables you to toggle menu item visibility (Firefox bug 1482529).
  • Items created using the {{WebExtAPIRef("menus")}} API now support access keys (Firefox bug 1320462).
  • The targetUrlPatterns parameter of {{WebExtApiRef("menus.create()")}} and {{WebExtApiRef("menus.update()")}} now supports any URL scheme, even those that are usually not allowed in a match pattern (Firefox bug 1280370).
  • When a tab context menu item is clicked, the "activeTab" permission is now granted for that tab, even if that's not the currently active tab (Firefox bug 1446956).

Other

  • {{WebExtAPIRef("commands.onCommand")}} is now treated as user input (Firefox bug 1408129).
  • The {{WebExtAPIRef("webRequest")}} API now enables you to filter for speculative connections (Firefox bug 1479565).
  • {{WebExtAPIRef("webRequest.SecurityInfo")}} adds two new properties, keaGroupName, and signatureSchemeName. This change was uplifted to Firefox 62 (Firefox bug 1471959).
  • {{WebExtAPIRef("cookies.Cookie")}} now includes a property indicating the SameSite state of the cookie. The {{WebExtAPIRef("cookies.SameSiteStatus")}} enumeration defines SameSite state values (Firefox bug 1351663).
  • Match patterns for URLs now explicitly match the "data" URL scheme (Firefox bug 1280370).