Firefox 65 for developers
This article provides information about the changes in Firefox 65 that will affect developers. Firefox 65 was released on January 29, 2019.
Changes for web developers
Developer tools
- The Flexbox inspector is now enabled by default.
- Support has been added to the JavaScript Debugger for XHR Breakpoints (Firefox bug 821610).
- Right-click on an item in the accessibility tree from the Accessibility viewer to print it as JSON to the JSON viewer.
- The color contrast display of the Accessibility Picker has been updated so that if a text's background is complex (e.g. a gradient or complex image), it shows a range of color contrast values.
- The Headers tab of the Network Monitor now displays the Referrer Policy for the selected request (Firefox bug 1496742).
- When displaying stack traces (e.g. in console logs or the JavaScript debugger), calls to framework methods are identified and collapsed by default, making it easier to home in on your code.
- In the same fashion as native terminals, you can now use reverse search to find entries in your JavaScript console history (
F9
on Windows/Linux orCtrl
+R
on macOS, then type a search term, followed byCtrl
+R
/Ctrl
+S
to toggle through results). - The JavaScript console's
$0
shortcut (references the currently inspected element on the page) now has autocomplete available, so for example you could type$0.te
to get autocomplete suggestions for properties like$0.textContent
. - The edits you make in the Rules view of the Inspector are now listed in the Changes panel (Firefox bug 1503920).
HTML
- Events are now dispatched on disabled HTML elements, i.e.
<button>
,<fieldset>
,<input>
,<select>
, and<textarea>
elements withdisabled
attributes set on them (Firefox bug 329509). - Removing the
src
attribute of an<iframe>
element now causesabout:blank
to be loaded into it, giving it parity with Chrome and Safari (Firefox bug 1507842). Previously removingsrc
had no effect on theiframe
content. - We have added support for the
referrerpolicy
attribute on<script>
elements (Firefox bug 1460920).
CSS
-
The
image-rendering
property'scrisp-edges
value has now been unprefixed (Firefox bug 1496617). -
A
scrollbar-color
value ofauto
now resolves toauto
, rather than two colors (Firefox bug 1501418). -
The
break-*
properties have been implemented, and the legacypage-break-*
properties have been aliased to them (Firefox bug 775618):break-before
is now an alias forpage-break-before
.break-after
is now an alias forpage-break-after
.break-inside
is now an alias forpage-break-inside
.
-
The
overflow-wrap
property'sanywhere
value has been implemented (Firefox bug 1505786). -
The new step position keywords
jump-start
,jump-end
,jump-none
, andjump-both
— usable inside thesteps()
timing function — have been implemented (Firefox bug 1496619). This also coincides with the removal of theframes()
timing function, which was the previous way of implementing such functionality, now deprecated. -
Some new
-webkit-appearance
values have been added, for compatibility with other browsers. In particular:meter
, which is now used as the default value for<meter>
elements in UA stylesheets. The existing valuemeterbar
is now an alias formeter
(Firefox bug 1501483).progress-bar
, which is now used as the default value for<progress>
elements in UA stylesheets. The existing valueprogressbar
is now an alias forprogress-bar
(Firefox bug 1501506).textarea
, which is now used as the default value for<textarea>
elements in UA stylesheets. The existing valuetextfield-multiline
is now an alias fortextarea
(Firefox bug 1507905).
-
The behavior of
user-select
has been changed to make it align more with other browsers (Firefox bug 1506547). Specifically:-
user-select: all
set on an element no longer overrides other values ofuser-select
set on children of that element. So for example in the following snippet:html<div style="-webkit-user-select: all"> All <div style="-webkit-user-select: none">None</div> </div>
The
<div>
withnone
set on it is now non-selectable. Previously this value would have been overridden by theall
value set on the parent element. -
non-
contenteditable
elements nested insidecontenteditable
elements are now selectable. -
user-select
now behaves consistently inside and outside shadow DOM. -
The proprietary
-moz-text
value has been removed.
-
-
CSS environment variables (the
env()
function) have been implemented (Firefox bug 1462233).
Removals
- The
layout.css.shape-outside.enabled
pref has been removed;shape-outside
,shape-margin
, andshape-image-threshold
can no longer be disabled inabout:config
(Firefox bug 1504387). - Several Firefox-only values of the
user-select
property have been removed —-moz-all
,-moz-text
,tri-state
,element
,elements
, andtoggle
. See Firefox bug 1492958 and Firefox bug 1506547. - As mentioned above, the
frames()
timing function has been removed (Firefox bug 1496619).
SVG
No changes.
JavaScript
Intl.RelativeTimeFormat
is now supported (Firefox bug 1504334).- Strings now have a maximum length of
2**30 - 2
(~1GB) instead of2**28 - 1
(~256MB) (Firefox bug 1509542). - The
globalThis
property, which always refers to the top-level global object, has been implemented (Firefox bug 1317422).
APIs
New APIs
- Readable Streams have been enabled by default (Firefox bug 1505122).
- The Storage Access API has been enabled by default (Firefox bug 1513021).
DOM
Performance.toJSON()
has been exposed to Web Workers (Firefox bug 1504958).XMLHttpRequest
requests will now throw aNetworkError
if the requested content type is aBlob
, and the request method is notGET
(Firefox bug 1502599).- The
-moz-
prefixed versions of many of the Fullscreen API features have been deprecated, and will now display deprecation warnings in the JavaScript console when encountered (Firefox bug 1504946). Window.createImageBitmap()
andWorkerGlobalScope.createImageBitmap()
now supports SVG images (SVGImageElement
) as an image source (Firefox bug 1500768).
DOM events
- Going forward, only one
Window.open()
call is allowed per event (Firefox bug 675574). - The
keyup
andkeydown
events are now fired during IME composition, to improve cross-browser compatibility for CJKT users (Firefox bug 354358.
Web workers
SharedWorkerGlobalScope.connect
's event object is aMessageEvent
instance — itsdata
property is now an empty string value rather thannull
(Firefox bug 1508824).
Fetch and Service workers
- The
Response.redirect()
method now correctly throws aTypeError
if a non-valid URL is specified as the first parameter (Firefox bug 1503276). - The
ServiceWorkerContainer.register()
andWorkerGlobalScope.importScripts()
(when used by a service worker) methods will now accept any files with a valid JavaScript MIME type (Firefox bug 1354577). - The
FetchEvent.replacesClientId
andFetchEvent.resultingClientId
properties are now supported (Firefox bug 1264177). - The
ServiceWorkerGlobalScope.onmessageerror
andServiceWorkerContainer.onmessageerror
handler properties have been implemented (Firefox bug 1399446). - The
Origin
header is no longer set on Fetch requests with a method ofHEAD
orGET
(Firefox bug 1508661).
Media, Web Audio, and WebRTC
- The WebRTC
RTCIceCandidateStats
dictionary has been updated according to the latest spec changes (Firefox bug 1324788, Firefox bug 1489040; RTCIceCandidateStats has been updated to the latest spec for more details on exactly what has changed). - The
MediaRecorder
pause
andresume
events (and their corresponding event handler properties were not previously implemented, even though compatibility tables claimed they had been. They have now been implemented (Firefox bug 1458538, Firefox bug 1514016).
Canvas and WebGL
- The WebGL
EXT_texture_compression_bptc
andEXT_texture_compression_rgtc
texture compression extensions have been exposed to WebGL1 and WebGL2 contexts (Firefox bug 1507263).
Removals
- Mutation events have been disabled in shadow trees (Firefox bug 1489858).
- The non-standard
MediaStream
propertycurrentTime
has been removed (Firefox bug 1502927). - The
dom.webcomponents.shadowdom.enabled
anddom.webcomponents.customelements.enabled
prefs have been removed — Shadow DOM and Custom Elements can no longer be disabled inabout:config
(Firefox bug 1503019). - The non-standard DOM
text
event — fired to notify the browser editor UI of IME composition string data and selection range — has been removed (Firefox bug 1288640). - The
keypress
event is no longer fired for non-printable keys (Firefox bug 968056), except for theEnter
key, and theShift
+Enter
andCtrl
+Enter
key combinations (these were kept for cross-browser compatibility purposes).
Security
- Additional CORS restrictions are now being enforced on allowable request headers (Firefox bug 1483815, see also whatwg fetch issue 382: CORS-safelisted request headers should be restricted according to RFC 7231 for more details).
Networking
No changes.
Plugins
No changes.
WebDriver conformance (Marionette)
API changes
WebDriver:ElementSendKeys
now handles<input type=file>
more relaxed for interactability checks, and allows those elements to be hidden without raising anot interactable
error anymore. If a strict interactability check is wanted the capabilitystrictFileInteractability
can be used (Firefox bug 1502864).
Bug fixes
- The window manipulation commands
WebDriver:FullscreenWindow
,WebDriver:MinimizeWindow
,WebDriver:MaximizeWindow
, andWebDriver:SetWindowRect
have been made more stable (Firefox bug 1492499). It means that under special conditions they don't cause an infinite hang anymore, but instead timeout after 5s if the requested window state cannot be reached (Firefox bug 1521527). WebDriver:ElementClick
now correctly calculates the center point of the element to click, which allows interactions with dimensions of 1x1 pixels (Firefox bug 1499360).
Others
- For
unexpected alert open
errors more informative messages are provided (Firefox bug 1502268).
Other
-
Support for WebP images has been added (Firefox bug 1294490).
- In addition, to facilitate cross-browser compatibility in certain situations the WebP MIMEType (
image/webp
) has been added to the standard HTTP RequestAccept
header for HTML files (Firefox bug 1507691).
- In addition, to facilitate cross-browser compatibility in certain situations the WebP MIMEType (
-
The AV1 codec is now supported by default on Windows (Firefox bug 1452146).
Changes for add-on developers
API changes
Tabs
-
The tabs API# has been enhanced to support tab successors — a tab can have a successor assigned to it, which is the ID of the tab that will be active once it is closed (Firefox bug 1500479, also see this blog post for more information). In particular:
- The
tabs.Tab
type now has asuccessorId
property, which can be used to store/retrieve the ID of the tab's successor. - The
tabs.onActivated
event listener's callback has a new parameter available,previousTabId
, which contains the ID of the previous activated tab, if it is still open. - The
tabs.update()
function'supdateProperties
object has a new optional property available on it,successorTabId
, so can be used to update it. successorTabId
is also returned by functions liketabs.get()
andtabs.query()
.- The new function
tabs.moveInSuccession()
allows manipulation of tab successors in bulk.
- The
Manifest changes
No changes.
Other
- The
headerURL
/theme_frame
properties for WebExtension themes are now supported on Firefox for Android (Firefox bug 1429488).
See also
- Hacks release post: Firefox 65: WebP support, Flexbox Inspector, new tooling & platform updates
Older versions
- Firefox 64 for developers
- Firefox 63 for developers
- Firefox 62 for developers
- Firefox 61 for developers
- Firefox 60 for developers
- Firefox 59 for developers
- Firefox 58 for developers
- Firefox 57 for developers
- Firefox 56 for developers
- Firefox 55 for developers
- Firefox 54 for developers
- Firefox 53 for developers
- Firefox 52 for developers
- Firefox 51 for developers
- Firefox 50 for developers
- Firefox 49 for developers
- Firefox 48 for developers
- Firefox 47 for developers
- Firefox 46 for developers
- Firefox 45 for developers
- Firefox 44 for developers
- Firefox 43 for developers
- Firefox 42 for developers
- Firefox 41 for developers
- Firefox 40 for developers
- Firefox 39 for developers
- Firefox 38 for developers
- Firefox 37 for developers
- Firefox 36 for developers
- Firefox 35 for developers
- Firefox 34 for developers