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- Affecting
@-moz-document url-prefix()CSS hack will no longer work - Affecting Flash plug-in support will be removed in 2020
- Affecting Symantec, Geo
Trust, Rapid SSL, Thawte, Verisign certificates will all be distrusted in October 2018 - Setting cookies with
<meta http-equiv>will no longer be allowed - Web Crypto API will not be available on insecure sites
- Web
VR will not be available on insecure sites <keygen>support will be droppedstorageoption forindexedhas been removedDB.open() - Non-standard
typeargument fordocumentis no longer supported.open() - Most of non-standard CSS
displayvalues have been dropped DOMPointconstructor no longer acceptsDOMPointas argument;Init DOMQuadhas been deprecated.bounds DOMAttrandModified DOMSubtreeevents are no longer fired whenModified styleattribute is changed via CSSOM- Ambient light and proximity sensor APIs have been disabled
navigatorcan no longer be used on insecure sites.register Protocol Handler() - Application Cache can no longer be used on insecure sites
::selectionpseudo-element has been unprefixednavigatorhas been removed.register Content Handler() removestreamevent has been removed fromRTCPeerConnection Fileis no longer available in service workersReader Sync online/offlineevents are no longer fired ondocumentanddocument.body - CSP
referrerdirective has been removed - Support for
Eventhas been added.prototype .src Element CSSStyleand related interfaces have been removedDeclaration .get Property CSSValue() - Type of
CSSinterface has been changed fromfunctiontoobject justify-items:autohas been renamed tolegacykeydownandkeyupevents will soon be fired during IME compositiongrid-gap,grid-row-gapandgrid-column-gapproperties have been unprefixed- Service workers and push notifications are disabled on Firefox 60 ESR
Filehas been removed.last Modified Date SVGViewhas been removedElement .prototype .view Target - Touch event listeners are now passive by default, making scrolling faster on mobile
SVGNumberno longer comes with constructorURL.createno longer acceptsObject URL() Mediaas argumentStream pixeland similar properties have been removed fromUnit To Millimeter X SVGSVGElement- Remote JAR support has been completely removed
- Affecting Basic auth credentials are now encoded in UTF-8 instead of ISO-8859-1
- Loading FTP resources within web page is no longer allowed
@-moz-documentsupport has been dropped except for emptyurl-prefix()CSSStylehas been deprecatedDeclaration .get Property CSSValue() - Affecting Symantec certificates issued before June 2016 are now distrusted
- Loading insecure content within plug-in embedded on secure site has been deprecated
storageoption forindexedhas been deprecatedDB.open() Datahas been renamed toChannel RTCDataChannel - Affecting Non-printable keys will soon stop firing
keypressevent - Affecting Symantec-issued certificates will soon be distrusted
- Various device sensor APIs are now deprecated
- Affecting
<script>with version parameter will no longer be loaded - Legacy
-moz-transformsyntax support has been removed -moz-user-input:enabledanddisabledare no longer supported- Rich text editor’s newline behaviour has been changed, now generates
<div>instead of<br> Arrayis now enabled again.prototype .values() - Support for
registeron insecure sites has been deprecatedProtocol Handler() - Support for application cache on insecure sites has been deprecated
- Affecting Data URLs are now treated as unique origins
navigatorhas been deprecated.register Content Handler() windowhas been removed.sidebar .add Search Engine() - Expression closure support has been removed
feedandpcastprotocols are no longer supported- SMIL
accesssupport has been removedKey navigatorhas been removed.moz Notification - HTTP auth dialog can no longer be triggered by cross-origin images
-moz-border-*-colorsproperties have been removed- Conditional
catchclauses are no longer supported mozmmCSS unit is no longer supportedHTMLMediahas been removedElement .moz Autoplay Enabled - Data URL navigations on top level window will now be blocked
Eventhas been removed.get Prevent Default - Array/generator comprehension support has been removed
- Regressed
page-break-before/afterin print stylesheet may lead to lack or overlap of elements - Regressed Certain multi-column layouts may balance unevenly or lack elements randomly
- Affecting HTML form’s
actionproperty now returns document URL ifactionattribute is empty or missing <a>elements can no longer be used as image map regions- Prefixed Web
GL extensions are no longer supported - Legacy generator support has been removed
Datehas been removed.prototype .to Locale Format - Regressed Preloaded stylesheets are not applied to the page
- Regressed Web
RTC video may stop in low-bandwidth conditions Objecthas been removed.prototype .watch HTMLMediahas been removedElement .moz Src Object - Non-standard system metric pseudo-classes and media features have been removed
- Prefixed
XMLHttpresponse types includingRequest moz-blobare no longer supported DOMErrorhas been removed in favour ofDOMException- Firefox 57 introduces new CSS engine, changes some behaviours
locationno longer escapes single quotes.hash - Flash plug-in is no longer supported by Firefox for Android
- Legacy iterator protocol has been removed
- Japanese default fonts have been changed
windowwill be removed.content - Regressed Some Flash contents including games and video players are broken on Firefox 55
- Regressed Firefox 55 breaks file upload on certain sites
Objecthas been deprecated.prototype .watch - Social API has been completely removed
for-each-inloop support has been removedDatehas been deprecated.prototype .to Locale Format mozandDont Offer Data Channel mozhave been removed fromBundle Only RTCOfferOptions - HTML context menu support will be removed
- Scoped stylesheets are no longer supported
<isindex>support has been dropped<applet>support has been dropped- Regressed Page is automatically closed when
windowtriggers file download.open() - Intl API now uses browser locale by default on all platforms
- Regressed Checkboxes and radio buttons are not displayed when
MSThemeisCompatible no navigatorwill soon require.request Media Key System Access() Mediaas configurationsKey System Capabilities RTCInboundhas been unprefixedRTPStream Stats .moz Rtt documentno longer supports various obsolete events.create Event() autoandGain Control noisemedia track constraints have been unprefixedSuppression - Affecting Flash plug-in content now requires click to activate
- Support for EME on insecure contexts has been deprecated
Mediahas been removedKey Session .key System - Regressed Form validation error messages disappear quickly
windowdialog support has been dropped.find() - Reverted
gethas been removedDefault Computed Style() SVGZoomhas been removedEvent - Affecting Remote JAR support has been disabled again
- Regressed Predictive prefetch makes duplicate HTTP requests in iframes, causing false ad impressions
- Regressed
XMLHttpmay return corrupt data for large blobsRequest xml:baseforstyleattribute has been disabled- Regressed CSS transitions may not work smoothly when
opacityis used with other property scroll,X scroll,Y page,XOffset pagenow return double instead of integerYOffset UIEventhas been removed.is Char - Regressed NTLM authentication may fail against HTTPS site
- Regressed Flex items are not sorted according to
orderif separated by abspos sibling - TLS CBC-mode ECDSA ciphers have been removed
- Callback-based
RTCPeerhas been deprecatedConnection .get Stats() - Affecting Flash can now be loaded only from HTTP/HTTPS
- CSP
referrerdirective has been deprecated - Form validation no longer runs on hidden
<input>elements - Use of Geolocation API is now limited to secure sites
:-moz-table-border-nonzeropseudo-class has been removed- Affecting URLs with no host name are now treated as invalid
xml:baseattribute has been deprecated- Transparent RGBA colour values are no longer serialized to
transparentkeyword eventnow returns.time Stamp DOMHighby defaultRes Time Stamp -moz-appearanceproperty has been removed- Service workers and push notifications are disabled on Firefox 52 ESR
- Prefixed
unicode-bidivalues are no longer supported - NPN support has been removed
URL.createhas been deprecatedObject URL(stream) - Insecure login forms now disable autofill, show warning beneath input control
-moz-calc()has been removed- Affecting Certain secure sites are broken due to outdated version of NSS
- Affecting
Datais nowTransfer .types DOMStringinstead ofList Array - Non-standard
Array/Stringgenerics have been deprecated - Regressed
<img>in<template>or<button>is not loaded properly Arrayhas been removedBuffer .slice - Insecure password input warning has been enabled by default
- Regressed
border-imageis broken under certain circumstances - Regressed Uploading file using XHR prepends slash to
filename -moz-text-align-lastproperty has been removed:-moz-dirpseudo-class has been removed- Affecting RC4 support has been completely removed
Arrayhas been deprecatedBuffer .slice Headershas been removed in favour of.get All getnow returning all valuesnavigatorand.plugins mimeare now unenumerableTypes - Battery Status API has been removed
use strictcan no longer be used in function with non-simple parameters- Affecting New Wo
Sign and Start Com certificates will no longer be accepted - Affecting SHA-1 certificates issued by public CA will no longer be accepted
- Regressed Flash objects are not positioned properly according to
salignattribute - Regressed Some Flash content is broken due to async rendering mode
- Array destructuring with rest element will throw if trailing comma follows
- Fullscreen request is now only allowed on HTML elements,
<svg>and<math> - Reverted
loadevent is no longer fired on<iframe>with JavaScript srcreturning non-string value - Offscreen Canvas
transferhas been renamed;Image Bitmap() Imagemay be disabled soonBitmap Rendering Context - Prefixed CSS3 multi-column properties will be removed
- CSS3 multi-column properties have been unprefixed
- Affecting Increased HPACK maximum table size breaks specific servers
- Affecting Touch event support has been re-enabled on Windows desktop
SVGDocumenthas been removed- Canvas 2D
mozandDash mozhave been removedDash Offset - Affecting Plug-in support has been dropped other than Flash
-moz-use-text-colorCSS colour keyword has been dropped- Regressed Specific Canvas text effects are not rendered properly
- Regressed Setting
documentdoesn’t change the port, may cause permission errors.domain - Reverted
Arraybreaks some legacy apps.prototype .values() - Caret will be placed at the end when textbox automatically gets focus
- Affecting
<img>with emptysrcwill fireerrorevent - Alarm API has been removed
::placeholderpseudo-element and:placeholder-shownpseudo-class have been unprefixed- Prefixed Page Visibility API has been removed
Acceptheader for XHR has been simplified- Java
Script served with wrong MIME type will be blocked haswill always returnFeature trueeven for SVG- Canvas 2D
imagehas been unprefixedSmoothing Enabled - Non-standard Simple Push API has been removed
- Workers will no longer dispatch
closeevent - Invalid XML document no longer contains
<parseerror>when retrieved with XHR - Some non-essential Flash plug-in content will be blocked
Permissionshas been disabled.revoke() - Social Service Worker API has been removed
- Social API has been removed except the sharing functionality
- Returning non-object value from
iteratorwill throw.next() - Canvas 2D
mozhas been removedFill Rule - Legacy generator function is no longer allowed in method definitions
RTCPeerhas been removedConnection .remove Stream - SVG
preserveno longer supportsAspect Ratio deferoption - SPDY/3.1 has been disabled
- Network error for async XHR now fires
errorevent instead of throwing,getwill be emptyAll Response Headers - Prefixed Pointer Lock API has been removed
:any-linkCSS pseudo-class has been unprefixed- Affecting Legacy non-standard drag events have been removed
unicode-bidivalues have been unprefixed:-moz-full-screen-ancestorhas been removed- Reverted
navigatorand.plugins navigatorno longer list Flash when it’s click-to-activate.mime Types RTCDatahas been removedChannel .stream box-sizing:padding-boxhas been removed- Affecting Flash is forced windowless mode on Firefox for 64-bit Windows, affecting Stage 3D
- Some
Keyboardvalues have been renamedEvent .key VTTCuenow uses.position Align Positioninstead ofAlign Setting AlignSetting - Affecting
windowhas been removed.show Modal Dialog navigatorhas been removed in favour of async.battery getmethodBattery <label>no longer hasformattributeFilehas been deprecated.last Modified Date - Affecting Support for
#RGBAcolour values may validate previously invalid values text-align-lasthas been unprefixedDatehandling of 2-digit years has been changed to be Chrome compatible.parse RTCPeer,Connection .get Local Streams gethave been deprecatedRemote Streams - Pop-up window is now scrollable by default
- Microdata API has been removed
- Regressed POST request fails on certain sites, showing connection reset page
fetchandRequestnow throws if redirect is detected when in non-followredirect mode<altis no longer supportedGlyph> :dirCSS pseudo-class has been unprefixed- Invalid
<track kind>will be treated asmetadatainstead ofsubtitles - Affecting Non-standard
flagsargument has been removed fromStringsearch methods - Regressed Combination of CSS
perspectiveandz-indexleads to wrong layering - Affecting
<input pattern>now setsuflag for regular expressions - Affecting All plug-ins other than Flash are now defaulted to click-to-activate
- Regressed Web
GL point sprites are not rendered properly in certain environments Touchhas been removedList .identified Touch - Affecting
<select>value is now properly updated when non-existent option is programmatically selected - Affecting
Permissions’s.query useroption has been renamed toVisible userVisible Only local,Name namespace,URI prefixproperties have been moved fromNodetoElement- Affecting Disabled form controls now trigger
mouseoverand similar mouse events Stringhas been removed in favour of.prototype .contains includes- Regressed Submitting empty file input control results in no
Content-Type RTCStatshas becomeReport Map-like object- Affecting Defining non-configurable property on
windowwill throw (currently only on Nightly and Developer Edition) - Affecting
Filefails when file is updated after initial readingReader .read As Text - Affecting Loading cross-origin worker now fires
errorevent instead of throwing; worker in sandboxed iframe no longer allowed - Non-standard Web Payments API has been removed
- Setting properties on a primitive now throws in strict mode
Textno longer supports UTF-16Encoder - Regressed Some elements in interactive SVG become invisible under certain conditions
- Regressed Images are not updated in some cases when
srcsetis dynamically changed Regglobal switch has been removedExp .multiline - Firefox OS APIs have been hidden from Web content
CSSKeyframeandRule CSSKeyframeshave been unprefixedRule - Affecting Dedicated workers no longer inherit CSP from parent document unless embedded
__defineandGetter__ __definecan no longer be called at the global scopeSetter__ - Legacy Proxy API has been removed
- Regressed Various sites are broken when third-party cookies are blocked
- Image with
idno longer appears ondocumentunless it hasnameas well Acceptheader for images has been simplified- Callback function of
Notificationhas been deprecated.request Permission() - Elements with
dirattribute will haveunicode-bidi:isolate - Service Workers have been disabled in Firefox 45 ESR
- Affecting Fullscreen API has been unprefixed in non-release builds
- Events on
<option>no longer bubble up to<select>in multi-process Firefox Proxy’senumeratehandler has been removed- Web App Runtime has been removed from Firefox for desktop and Android
- Affecting Non-standard
flagsargument ofStringmethods has been disabled in non-release builds - Reverted
HTMLCanvasno longer accepts non-object context attributesElement .get Context - Regressed Cross-site
XMLHttpis blocked if Service Worker is used withoutRequest fetchevent handler - Cache API now rejects unsuccessful responses
- Affecting Some Web fonts may not be displayed due to stricter validation
- Reverted Whitespaces are no longer allowed in cookie names
view-source:URLs can no longer be linked from Web pages- Redeclaration of block-scoped functions has been deprecated
clearmethod has been removed fromWeakandMap WeakSet - Application Cache support will be removed
- Scroll-linked positioning effects may not work well with async scrolling, console warns
- Legacy array/generator comprehension syntaxes have been removed
- Regressed MP3 streaming is awkward on Firefox 41 and later
- Regressed
thisin getter/setter doesn’t work as expected in certain circumstances - Affecting
showhas been disabled in multi-process FirefoxModal Dialog Regglobal switch has been deprecatedExp .multiline - Regressed Animated GIFs are drawn partially if downscaled and hidden at first
- Regressed Rounded objects with fixed background image are not trimmed properly
- Regressed Geolocation API is not working on Firefox 43 and 44 Beta
- Reverted
performancein workers is now based on the worker’s creation time.now documentnow lowercases the input.create Attribute searchis now only onParams URL- CSP directive
frame-srchas been deprecated in favour ofchild-src - EV certs valid for more than 27 months will be treated as DV certs
- Regressed CSS classes applied to wrong elements
- Non-standard
Array/Stringgenerics will be removed - Reverted
jarprotocol support has been disabled by default - Expression closures are now deprecated
- Line breaks in HTTP/2 headers are no longer allowed
- Nested
<optgroup>s are no longer allowed letstatement no longer requires explicit JavaScript version - Several properties will be removed from
SVGSVGElement - Prefixed CSS Animations, Transforms, Transitions support will be removed
- Prefixed
cursortypes will be removed -moz-border-imagewill be removed-moz-outline-radiuswill be removed- Affecting Insecure HTTP will be deprecated
- Affecting Third-party cookies may be disabled by default in the future
- Affecting RFC 2047 support for
Content-Dispositionheader will be removed - Build ID in UA string is now frozen at
20100101 - Language names in
Accept-Languageheader are now always canonicalized hspace/vspaceattributes on<table>will no longer be supportedElementwill be removed.moz Matches Selector Mousewill be removedEvent .moz Pressure windowwill be removed.sidebar navigatorwill be removed.build ID IDBObjectand related methods have been unprefixedStore .get All - Equifax 1024-bit root certificate will no longer be trusted
letblock support has been removed- Web Storage, Indexed
DB, Cache API now obey third-party cookies preference - Reverted
getnow matchesElements By Tag Name localinstead ofName tagName XMLHttpnow sends HTML document asRequest text/htmlinstead ofapplication/xmlXMLHttpis no longer available in Service WorkersRequest - Regressed Cross-frame
for-inloop is not working - Regressed
getreturnsAttribute nullfor attributes created withsetand containing upper-case characters in nameAttribute Node - Affecting Non-HTTPS sites containing login form will be marked insecure (currently only on Nightly, Developer Edition and early Beta)
- Regressed IDN URLs are not redirected properly
- Regressed
:activepseudo-class is not working on textbox - Images with
idno longer appear aswindowproperties - Regressed Link with line break in hash part is broken
- Regressed 303 and 307 redirects after 302 are not followed
- Several unimplemented CSS properties have been dropped
Documenthas been removedType .internal Subset - Affecting RC4 is now completely disabled by default
- Calling typed array constructors without
newwill throw - Variables defined with
constandletare no longer properties onwindow; redeclaration withletwill throw - Documents in
<frame>or<object>can no longer request fullscreen - Several internal CSS properties have been removed
dialogoption forwindowis no longer supported.open() - Regressed CSS cascading may go wrong when style is dynamically updated
- Regressed Canvas fails to render emojis on OS X
- CSS
position:fixednow always creates stacking context Mediahas been deprecatedStream .stop() - Private Browsing now comes with Tracking Protection
beforeunloadconfirmation dialog will no longer be displayed unless user has interacted with the page- ICO images now use the largest resource as the intrinsic size
- Web
RTC interfaces have been unprefixed - Application Cache API has been deprecated
- Reverted RC4 is now allowed only on whitelisted sites
- Service Workers
Extendableimplementation has been updatedEvent .wait Until - ECMAScript
argumentsimplementation has been updated - Direction-independent CSS properies have been unprefixed
fetch()andnew Request()now throws if URL includes credentials- Affecting Sherlock search plug-ins are no longer supported
- Affecting CSS
floatbugs have been fixed - Affecting RC4 is no longer supported on Nightly and Developer Edition
- Undefined pseudo-header fields are no longer accepted in HTTP/2
CSSRulenow returns unprefixed.css Text writing-mode-aware properties__nois no longer supportedSuch Method__ - Wrong Referrer Policy implementation has been corrected
- HTTP/2 draft is no longer supported
X-Content-Durationheader for Ogg media is no longer supportedhyphensproperty has been unprefixednavigatorhas been deprecated in favour of async.battery getmethodBattery - SHA-1-based certificates with validity period from 2016 will not be validated
- Screen Orientation API has been unprefixed
- Constraint-like
RTCOfferare no longer supportedOptions - Affecting
eventnow returns.time Stamp DOMHighon Nightly/Aurora for LinuxRes Time Stamp - Affecting
requestin non-visible iframes is now throttledAnimation Frame - Regressed
<option>cannot be selected in certain circumstances - Regressed
<input>has widened on Japanese Windows 7 - Reverted Some plug-in content may not be loaded due to async initialization
- Calling
Map/Set/WeakwithoutMap newwill throw - EV certs with overly long validity periods will be treated as DV certs
- Regressed Multi-process is enabled by default on the Developer Edition
-moz-prefixed gradient support to be removed, make sure you have unprefixed gradientsHTMLMediahas been unprefixedElement .src Object RTCIcehas been unprefixedCandidate Pair Stats .priority Requesthas been removed.context mozand related APIs have been removedRequest Animation Frame - Affecting
Mouse/Event .offset X Yhas been implemented; Google Maps API behaves wrongly - Regressed Nested
contenteditableelements cannot be selected nor edited properly - Affecting 64-bit Firefox for Windows is officially available, Flash and Silverlight are the only supported plug-ins
- Affecting Firefox for Android UA string now has the Android version
- Math
ML default font has been changed - Method definitions now require curly brackets, cannot be constructors
- Parenthesized destructuring patterns are no longer allowed
- Affecting SVG favicon is supported; be careful with the order of
<link>s - Service Worker Cache API added several global objects
Mouse/Event .movement X Yhave been unprefixed- Affecting
Reghas become prototype accessor propertyExp .source - Affecting
URLUtilsno longer decodes fragment.hash URLUtilsis now readonly.search Params documentfor cut, copy and paste no longer throws.exec Command initandClose Event createhave been removedEvent('Close Event') letexpression support has been dropped- Calling
DatawithoutView newwill throw - Affecting Default style of
<abbr>/<acronym>has been changed - Destructuring
for-inloop has been removed - Reverted HTTP auth dialog can no longer be triggered by cross-origin resources
- Initial value of
-moz-orienthas been changed - Affecting Initializer in
for-of/inloop head declaration is no longer allowed - Unreachable code after
returnstatement will be warned - Affecting Wildcard in CSP policy directives no longer allows
blob:,data:andfilesystem:resources -moz-text-decoration-*properties have been removedCSSCharsethas been removedRule Stringhas been renamed to.prototype .contains includesnegotiationneededevent is no longer suppressed before the first offer- Affecting DHE keys less than 1023-bit are no longer accepted
- Affecting Fetch API and Service Worker Cache API added several global objects
- Non-standard
flagsargument ofStringmethods has been deprecated - SSLv3 support has been removed
Proxyhanders may throw under specific conditionsXMLHttphas been removedRequest .send As Binary __nohas been deprecatedSuch Method__ - Affecting 1024-bit SSL certificates are no longer trusted
- 2
Keyboardlocation consts have been removedEvent - Calling
Map/Set/WeakwithoutMap newnow raises warning - Calling
Proxywithoutnewwill throw - Duplicated parameters may throw
- Setter with a rest parameter will throw
- Affecting Web
RTC now requires Perfect Forward Secrecy (PFS) Regnow returnsExp().source "(?:)"for empty regular expressions- Affecting
RegExp global,ignore,Case multilineandstickyproperties are now prototype accessor properties Weakimplementation has been updatedMap mozhas been removedIndexed DB - Certs with an absolute DNS ID or irregular wildcard are no longer supported
- Non-ECDSA DSS certificate support has been removed
- Parallel
JS has been removed (Nightly only) - Web Console now warns sites using SSLv3 and RC4
Keyboardvalues have been updated for the latest specEvent .key Peerhas been removedConnection Impl .connect Data Connection Stringhas been removed.prototype .quote XMLHttpnow always uses UTF-8 instead of the page charsetRequest .send for-each-inloops are now deprecatednulliterable forMapandSetis now ignored instead of throwing- CSS3 Text Decoration properties have been unprefixed,
text-decorationbecomes a shorthand - EV SSL certs with a shorter key length are no longer accepted
- Iterable objects now have
Symbolinstead of.iterator "@@iterator" - Affecting RC4 support has been deprecated
- Affecting SHA-1 support has been deprecated
- SPDY/3 support has been removed
:activeand:hoverare now applied only to links in the Quirks modeCSSRulenow returns two colons for pseudo-elements.selector Text Numbersupports binary and octal literalsconsthas been updated to be ES6 compatibledeletenow triggers “temporal dead zone”letblocks and expressions have been deprecated- Regressed CSP directives with sources containing capital letters are not applied
- Dropdown arrow on
<select>can again be hidden with-moz-appearance:none - ES6 object-literal
__proto__semantics have been implemented - Affecting ES6-compatible
letdisallows variable redeclaration - Regressed Kerberos authentication doesn’t work with aliases
- Affecting Legacy Crypto API has been removed
- Margin attributes on
<body>are now supported in all modes - Non-HTTP XHR now returns
200status code - Non-standard
elementextension has been added.style - Plugin Finder Service has been shut down
- Regressed Proxy authentication using cookies doesn’t work
- Some
RTCPeermethods soon require callbacksConnection - XHR
responseno longer includes fragmentURL Filehas been removed.moz Full Path Navigatorhas been removed.moz Is Locally Available Nodehas been moved to.has Attributes Elementcrossproperty now returnsOrigin anonymousifcrossoriginattribute is empty- Regressed
documentis not updated when.base URI <base>is removed from CSP-enabled pages - Affecting HTTP/2 is now enabled by default
- Affecting Initial value of
min-width/heighton flex items has been reverted toauto - Regex capture behaviour has been changed
- Affecting SSLv3 has been disabled
- URLs in an app manifest are now resolved against the manifest URL instead of the origin
Elementhas been unprefixed.matches Mozhas been renamed toNamed Attr Map NamedNode Map font-feature-settingshas been unprefixed while the newly enabledfont-variant-*properties are preferrednavigatoris now sorted in alphabetical order.plugins - Affecting
onpointer*properties are now hidden by default - Regressed Complex apps may throw an internal Java
Script error - Evaluation order of default parameters and functions inside function body is changed
- File
Handle API has been updated - Regressed Files may be downloaded partially from misconfigured servers
- Affecting Invalid
list-style-typenow leads to ordered list instead of unordered list - Legacy CSP implementation has been removed
- Reverted Legacy Crypto API has been disabled
- RSA certificates using weak signatures less than 1024-bit are no longer accepted
- Regressed Regex on Latin-1-only strings may cause a performance issue
- Several cipher suites have been disabled
- Some
Keyboardvalues have been deprecatedEvent .key HTMLTrack’sElement loadedevent has been renamed toloadNumberhas been removed.to Integer XMLHttphas been removedRequest .moz Background Request ethiopic-numerichas been unprefixedeventnow returns.time Stamp DOMHighon Nightly/Aurora for WindowsRes Time Stamp javascriptURLs specified as image sources are no longer executedtouchenterandtouchleaveevents have been dropped- Regressed Cache backend has been overhauled
- Several 1024-bit root certificates have been removed
HTMLCollectionno longer matches an empty string nameHTMLTablenow always inserts the row toElement .insert Row <tbody>Windowhas been removedUtils navigatornow returns a correct value.do Not Track new Document()now returnsDocumentinstead ofXMLDocumentonconnectionandonclosedconnectionhave been droppedwindowhas been removed.open Dialog - Audio Data API has been removed
- CSS variable prefix has been changed
- Regressed Certificate verification backend has been overhauled
- Affecting Global variables with the same name as
windowproperties now call the property setter when they are set - Network Information API has been disabled on desktop
- Unimplemented methods on
windowhave been removed.crypto ::-moz-math-stretchypseudo-element has been removed<track>has been implementedData,Container Event Browser,Feed Writer EventandListener Info XPathhave been removedNamespace XMLHttphas been deprecatedRequest .send As Binary navigatorhas been removed.moz Keyboard - Affecting
window,.home back,forwardmethods have been removed - Archive API has been disabled
- Regressed Code in
evaldoesn’t work when the Debugger is activated - DOM object constructors can no longer be called as functions
- Affecting Delay between touch and mouse events has been removed on responsive pages
- Firefox OS apps should always specify a viewport
<meta>tag - Incorrect
paddingimplementation on<select>has been fixed - Affecting NTLMv1 auth has been disabled, NTLM support on non-Windows platforms is now deprecated
- Plugin whitelist has been implemented
- Support for
Blobhas been dropped.moz Slice - Synchronous
XMLHttphas been deprecatedRequest - Use of the
Objectsetter should be avoided.__proto__ <form autocomplete="off">no longer prevents passwords from being savedKeyboardhas been removedEvent .DOM_VK_ENTER Mozinterface is no longer a global objectConnection Navigatorhas been disabled except on Firefox OS.request Wake Lock Videohas been removedPlayback Quality .total Frame Delay - Regressed
consolewill be overridden by a global variable with the same name - Affecting
line-heightis now applied to<input> position:relativeon table elements is no longer ignored- A minimum width has been set for the browser window
- Regressed Enter key on
<select>no longer fires thekeypressevent - Generator now returns
Iteratorinstead of throwingResult - Affecting HTTP connections now have a response timeout
- Affecting Incorrect
paddingimplementation on<textarea>has been fixed - Obsolete features have been dropped from
<pre> - Regressed PDF is printed as a blank page
- Affecting Per-domain Configurable Security Policies are no longer available
- Regressed Regex with 999998+ groups now raises an
InternalError - Affecting
<input type="number">has been implemented HTMLIFramenow returnsElement .sandbox DOMSettableToken List Keyboardvalues have been changedEvent .key Parallelhas been removedArray - Regressed
ProgressreturnsEvent .length Computable falseduring a file upload box-sizinghas been unprefixedcloneandNode importhas defaulted to shallow clonesNode displaystyleis no longer inherited from the root<math>elementmoz-webglcontext requests are no longer supported- Regressed
texfails on float texturesSub Image2D - Affecting
tomay return different values than beforeLocale String - Reverted
window,._content controllers,pkcs11andLoadhave been removedStatus - Audio Data API has been disabled
- Make sure the
deepargument is specified forcloneandNode importNode - Regressed Plug-in MIME types are written in lower-case
- SPDY/2 support has been dropped
- Affecting
Arrayand.keys Arrayhave been implemented.entries Historyobjects now throw if thedocumentis inactiveMozevent has been removedBefore Resize cannow returnsPlay Type('video/webm') 'maybe'showhas been deprecatedModal Dialog - Curly brackets are no longer allowed in
styleattributes - Deprecated
RTCPeerfunctionalities have been removedConnection - Iterator implementation has been updated to the latest spec
- Prefixed extensions have been deprecated
- Some CSS-related interfaces have been removed
-moz-graband-moz-grabbinghave been unprefixed-moz-rgba()and-moz-hsla()have been droppedStringand.match Stringnow reset.replace RegExp .last Index atobnow ignores whitespaces- Elements are no longer accessible with the old
idafter being changed - Affecting Java is now defaulted to Click-to-Activate
- Reserved words are no longer allowed as function names
- Setting
documentin a sandboxed.domain iframeis no longer allowed - Various non-standard interfaces have been removed
- Affecting XBL-related methods have been removed
-moz-text-blinkhas been removed in favour of-moz-text-decoration-line:blinkHTMLCanvashas been deprecatedElement .moz Get As File HTMLInputandElement .width heightnow return0when thetypeis notimageMessagehas been updatedEvent Userhas been removedData Handler - Constants of some Indexed
DB-related interfaces have been removed - Affecting ES6 array methods have been added
- Events in workers have been prefixed with
Worker - Various interfaces are no longer available on
window Documenthas been removedTouch HTMLVideohas been changed to a methodElement .video Playback Quality Imageand some XUL-related classes have been removedDocument Proxyhas been changed to be a functiongeolocationproperty of thenavigatorobject is now absent if the API is disabled- Affecting
preventonDefault keydownnow cancelskeypress yieldwithout a value has been deprecated- Obsolete event methods have been removed
- Prefixed
-moz-initialis no longer supported - Support for Sherlock search plug-ins has been deprecated
- Affecting Touch events support has been temporarily disabled on desktop
Gethas been removedSVGDocument HTMLCommandhas been droppedElement HTMLMediahas been removedElement .moz Load From Progressis no longer available in Web WorkersEvent .init Progress Event cursor: -moz-zoom-inand-moz-zoom-outhave been unprefixedfocusandblurevents are nowFocusEvent - Affecting Ability to add a sidebar panel has been dropped
- Affecting Blink effect with
text-decoration:blinkhas been dropped - CSP implementation has been updated for the final spec
- Cross-origin
contentreturnsDocument null - Instantiation of
AnimationandEvent TransitionusingEvent Documentis no longer allowed.create Event - Affecting Non-SSL active content on SSL pages is blocked by default
HTMLMediahas been removedElement .initial Time requestandAnimation Frame cancelhave been unprefixedAnimation Frame - Regressed
watch()throws aTypeon some interfacesError windowhas been removed.default Status - Audio Data API has been deprecated
- CSS3 Flexible Box has been enabled by default
- Regressed Cannot access to frames named
sidebar - HTML elements with tag names
bgsound,multicol, andimageno longer use theHTMLSpanintefaceElement - Initial value for
min-widthandmin-heighthas been changed back to0(even on flex items) - Reverted RFC 2047 encoding support for HTTP header field parameters has been removed
- Reverted Third-party cookies are blocked by default
- Unknown SVG Elements will be
SVGElement - XHR multipart response support has been removed
HTMLMediaandElement .crossorigin HTMLInputhave been renamedElement .inputmode LSProgresshas been removedEvent Namedhas been renamed toNode Map MozNamed Attr Map Nodehas been removed.attributes - Affecting
Nodeand.get User Data sethave been removedUser Data Nodehas been removed.is Supported Nodedoes nothingIterator .detach Parallelis now disabled in Beta, Release and ESRArray Progresshas been removedEvent .init Progress Event SVGEventhas been removedbackground-clipandbackground-originare now supported in thebackgroundshorthand property- Behaviour of
-moz-user-select:nonehas been changed to be consistent with-moz-user-select:-moz-noneand other browsers - Behaviour of
Stringwith no argument has been fixed.locale Compare - E4X support has been completely removed
- Indexed properties on the
windowobject (ie. iframes) are now enumerable - Regressed Proxyfied arrays without the
gettrap don’t work properly - Support of the
colsandlayoutproperties has been dropped fromtables - Unimplemented SVG features have dropped
CSSKeyframeshas been renamed toRule .insert Rule appendRule CSSStylewill throw when there are more than one ruleSheet .insert Rule HTMLInputhas been disabled by defaultElement .inputmode XMLHttpimplementation has been fixed to comply with the specRequest .set Request Header expandhas been removed fromEntity References NodeandIterator TreeWalker formandMethod formnow take an empty string as default valueEnctype mozhas been unprefixedAudio Context parsenow parses leading-zero strings as decimal, not octalInt - Affecting
scrollandWidth scrollare no longer affected byHeight overflow:visible - Affecting
windowno longer accepts indexed custom properties - When
undefinedis passed as an argument, the default parameter will be used if any Functionno longer counts default parameters.length - Archive API has been disabled by default
- CSS3 Flexible Box has been enabled by default, but still disabled on the Release channel
- XHR multipart support is now deprecated
CSSRuleconstants have been unprefixed.MOZ_KEYFRAME_RULE(S) HTMLElementmembers are no more available on the whole inheritage chaincontentandStyle Type contentproperties have been removedScript Type for eachloop has been virtually removed...in - Event listener objects are no longer accepted as values of
on*properties onXMLHttp,Request File,Reader Web, andSocket EventobjectsSource - Regressed Background images specified with
-moz-elementare not updated - Carbon NPAPI Support has been dropped
- Encoding API has been updated for the latest spec
- FYI: Preferences to disable prefixed properties have been added
- Flexbox has been unprefixed
- Key frame rule declarations with
!importantwill be ignored - Some event attributes are now limited to
bodyandframeset - XForms support has been removed
-moz-initialhas been unprefixed- Affecting
:-moz-placeholderpseudo-class has been replaced with the pseudo-element Content-Dispositionheader’snameparameter is no longer supportedElementnow returns.get Elements By* HTMLCollectionFilenow returns the current date if the modified date is unknown.last Modified Date Mapand.size Sethave been changed to properties.size createno longer throws exceptionsElement(null) documentimplementation has been updated for the latest spec.referrer has/Feature ismethods now always returnSupported true- FYI: Preferences to prevent non-SSL contents on SSL pages from loading have been added
- Initial value for
min-widthandmin-heighthas been changed toauto - Affecting Mootools 1.2.x is not compatible with Firefox 18 and newer
- Page Visibility API has been unprefixed
- Proxy API has been updated for the new spec
- Quality factor in request headers can now have 2 decimal places
Blobhas been removedBuilder MOZ_EXT_texture_filter_anisotropichas been unprefixed- Affecting
Mozevents were removed in favour of the standard touch eventsTouch - Affecting
Proxy-Connectionheader has gone XHR.getvalue has been changed to redundant UTF-8 byte charactersResponse Header() localquota has been limited to 5 MBStorage mozallowfullscreenhas been unprefixed- A Preference to disable HTTP Keep-Alive has been removed
- Creating interfaces without a constructor now throw exceptions
- Affecting E4X has been disabled
- Affecting Errors on colours and lengths are now only allowed for specific properties
- Exceptions thrown by
XHR.sethave been clarifiedRequest Header() - Reverted Gecko build date in the UA string has been replaced with the version number
- Image maps are now displayed as inline elements
- Initializing dispatched events no longer throw exceptions
- Line breaking code in the value of
XHR.gethas been changedAll Response Headers() - MIME types treated as Java
Script have increased - Reverted Privilege Manager has been disabled
- Showing dialogs are no longer allowed on page navigation events
- Site-specific UA string now can be set
- Web IDL dictionary (associative array) implementation has been updated for the latest spec
HTMLMediatype has been changedElement .src XHR.onuploadprogresshas been removed- Affecting Microdata API has added new properties to elements
- Exceptions of SVG and XPath have been standardized as
DOMException - Length values for
matrix()are now ignored - Lines are now wrapped between single-byte and double-byte spaces
- MD5 certificates are no longer accepted
- Media query resolutions are now calculated in CSS pixel unit
- Negative durations for transitions and animations will be ignored
- Several APIs have been unprefixed
- Table cell heights are now calculated properly regardless of the border
- UA string no longer contains patch level version number
- Various CSS properties have been unprefixed
- Web
Sockets disconnection now follows the latest spec CSSNamenow returns correct valueSpace Rule .type Smshas been replaced withRequest DOMRequestexecnow returnsCommand() falseif command is invalidjavaobject has been removedmozhas been disabledApps .install Package selectnow behaves differently with negative value.size