Firefox 88 for developers
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This article provides information about the changes in Firefox 88 that will affect developers. Firefox 88 is the current Beta version of Firefox, and will ship on April 20, 2021.
Changes for web developers
Developer Tools
Removals
HTML
Removals
CSS
- The
:user-valid
and:user-invalid
pseudo-classes have been implemented (bug 1694141). - The
image-set()
functional notation is now implemented forcontent
andcursor
(bug 1695402), and (bug 1695403). - The
image-set()
functional notation is now enabled (bug 1698133). - The default
monospace
font for MacOS has been changed to Menlo (bug 1342741). - The
collapse
value ofvisibility
is now implemented for ruby annotations (bug 1697529). - The
alternate
value forruby-position
is now implemented, and is the new initial value for the property (bug 1694748).
Removals
- The
:-moz-submit-invalid
pseudo-class has been hidden behind a preference, therefore removing it from web content (bug 1694129). - Default styling for the non-standard
:-moz-ui-invalid
and:-moz-ui-valid
has been removed (bug 1693969).
JavaScript
- Added support for RegExp match indices (bug 1519483).
Intl.DisplayNames()
andIntl.ListFormat()
now have stricter checking thatoptions
passed to the constructor are objects, and will throw an exception if a string or other primitive is used instead (bug 1696881).
Removals
HTTP
- FTP has been disabled on all releases (preference
network.ftp.enabled
now defaults tofalse
), with the intent of removing it altogether in Firefox 90 (bug 1691890). Complementing this change, the extension setting browserSettings.ftpProtocolEnabled has been made read-only, and web extensions can now register themselves as protocol handlers for FTP (bug 1626365).
Removals
Security
Removals
APIs
DOM
- Code can now use the new static method
AbortSignal.abort()
to return anAbortSignal
that is already set as aborted. This is useful when the signal is requested/created after the associated operation has already been aborted. For more information see bug 1698468.
Media, WebRTC, and Web Audio
Removals
- The Presentation API is no longer supported. For more information see bug 1697680.
WebAssembly
Removals
WebDriver conformance (Marionette)
Removals
Changes for add-on developers
url
can now be used to limit the properties for which thetabs.onUpdated
event is triggered (bug 1680279).
Removals
Older versions
- Firefox 87 for developers
- Firefox 86 for developers
- Firefox 85 for developers
- Firefox 84 for developers
- Firefox 83 for developers
- Firefox 82 for developers
- Firefox 81 for developers
- Firefox 80 for developers
- Firefox 79 for developers
- Firefox 78 for developers
- Firefox 77 for developers
- Firefox 76 for developers
- Firefox 75 for developers
- Firefox 74 for developers
- Firefox 73 for developers
- Firefox 72 for developers
- Firefox 71 for developers
- Firefox 70 for developers
- Firefox 69 for developers
- Firefox 68 for developers
- Firefox 67 for developers
- Firefox 66 for developers
- Firefox 65 for developers
- 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