Firefox 126 for developers
This article provides information about the changes in Firefox 126 that affect developers. Firefox 126 is the current Beta version of Firefox and ships on May 14, 2024.
Changes for web developers
Developer Tools
HTML
Removals
CSS
Removals
JavaScript
Removals
SVG
Removals
HTTP
- The
zstd
directive of theContent-Encoding
HTTP header is now supported, allowing decoding of server-sent content encoded with the Zstandard compression algorithm (Firefox bug 1871963).
Removals
Security
Removals
APIs
IDBFactory.databases()
is now supported for enumerating available IndexedDB API databases (Firefox bug 934640).- The
URL.parse()
static method is now supported for creatingURL
objects. This returnsnull
if the passed parameters do not define a validURL
, and can hence be used as a non-throwing alternative to creatingURL
object with theURL
constructor (Firefox bug 1823354). -
The Screen Wake Lock API is now supported, allowing a web application to request that the screen not be dimmed or locked while it is active. This is useful for navigation and reading applications, and other applications where the screen doesn't get regular tactile input when in use, which would otherwise keep the screen awake. The API is accessed through
Navigator.wakeLock
in secure contexts, which returns aWakeLock
. This can be used to request aWakeLockSentinel
that can be used to monitor the status of the wake lock, and release it manually. (Firefox bug 1589554, Firefox bug 1874849). - All
RTCIceCandidate
properties and methods are now supported and match the specification, with the exception of unimplemented properties:relayProtocol
andurl
.- The following properties were made read-only:
candidate
,sdpMid
,sdpMLineIndex
,usernameFragment
, - The following properties were added:
foundation
,component
,priority
,address
,protocol
,port
,type
,tcpType
,relatedAddress
,relatedPort
,usernameFragment
.
- The following properties were made read-only:
DOM
-
The ability to define states for custom elements and match them using CSS selectors is now available by default.
The custom states are represented as custom identifiers that can be added to or removed from the element's
ElementInternals.states
property (aCustomStateSet
). The CSS:state()
pseudo-class takes a custom identifier as an argument and matches custom elements if the identifier is present in their set of states. (Firefox bug 1887543).
Media, WebRTC, and Web Audio
Removals
- The marquee events
bounce
,finish
, andstart
have been removed fromHTMLMarqueeElement
, along with the corresponding event handler attributes defined on the<marquee>
HTML element (Firefox bug 1689705).
WebAssembly
Removals
WebDriver conformance (WebDriver BiDi, Marionette)
General
WebDriver BiDi
Marionette
Changes for add-on developers
- The
commands.onCommand
event now passes thetab
argument to the event listener. This enables extensions to apply a triggered shortcut to the page in which it was issued, without the need to call thetabs.query()
method (Firefox bug 1843866). - The
runtime.MessageSender
type now includes theorigin
property. This enables message or connection requests to see the page or frame that opened the connection. This is useful for identifying if the origin can be trusted if it isn't apparent from the URL (Firefox bug 1787379). - The
"webRequestAuthProvider"
permission is now supported. This provides compatibility with Chrome for requesting permission forwebRequest.onAuthRequired
in Manifest V3 (Firefox bug 1820569). - The
options_page
manifest key is provided as an alias of theoptions_ui
key. This has been provided to offer extensions better compatibility with Chrome (Firefox bug 1816960).
Removals
Other
Experimental web features
These features are newly shipped in Firefox 126 but are disabled by default. To experiment with them, search for the appropriate preference on the about:config
page and set it to true
. You can find more such features on the Experimental features page.
Older versions
- Firefox 125 for developers
- Firefox 124 for developers
- Firefox 123 for developers
- Firefox 122 for developers
- Firefox 121 for developers
- Firefox 120 for developers
- Firefox 119 for developers
- Firefox 118 for developers
- Firefox 117 for developers
- Firefox 116 for developers
- Firefox 115 for developers
- Firefox 114 for developers
- Firefox 113 for developers
- Firefox 112 for developers
- Firefox 111 for developers
- Firefox 110 for developers
- Firefox 109 for developers
- Firefox 108 for developers
- Firefox 107 for developers
- Firefox 106 for developers
- Firefox 105 for developers
- Firefox 104 for developers
- Firefox 103 for developers
- Firefox 102 for developers
- Firefox 101 for developers
- Firefox 100 for developers
- Firefox 99 for developers
- Firefox 98 for developers
- Firefox 97 for developers
- Firefox 96 for developers
- Firefox 95 for developers