Firefox 88 for developers
This article provides information about the changes in Firefox 88 that will affect developers. Firefox 88 was released on April 19, 2021.
Note: See also Never too late for Firefox 88 on Mozilla Hacks.
Changes for web developers
Developer Tools
- The toggle button for switching between raw and formatted response views has been implemented (Firefox bug 1693147). For examples, see Network request details > Response tab.
HTML
No changes.
CSS
- The
:user-valid
and:user-invalid
pseudo-classes have been implemented (Firefox bug 1694141). - The
image-set()
functional notation is now enabled (Firefox bug 1698133), and was made available forcontent
andcursor
in Firefox bug 1695402 and Firefox bug 1695403. - The default
monospace
font for MacOS has been changed to Menlo (Firefox bug 1342741). - The
collapse
value ofvisibility
is now implemented for ruby annotations (Firefox bug 1697529). - The
alternate
value forruby-position
has been implemented, and is the new initial value for the property (Firefox bug 1694748). - The
outline
CSS property has been updated to follow the outline created byborder-radius
. As part of this work the non-standard-moz-outline-radius
property has been removed. (Firefox bug 315209 and Firefox bug 1694146.)
Removals
- The
:-moz-submit-invalid
pseudo-class has been hidden behind a preference, thereby removing it from web content (Firefox bug 1694129). - Default styling for the non-standard
:-moz-ui-invalid
and:-moz-ui-valid
has been removed (Firefox bug 1693969).
JavaScript
- Added support for RegExp match indices (Firefox 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 (Firefox bug 1696881).
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 (Firefox bug 1691890). Complementing this change, the extension settingbrowserSettings.ftpProtocolEnabled
has been made read-only, and web extensions can now register themselves as protocol handlers for FTP (Firefox bug 1626365).
Security
No changes.
APIs
DOM
- Code can now use the new static method
AbortSignal.abort()
to return anAbortSignal
that is already set asaborted
(Firefox bug 1698468).
WebDriver conformance (Marionette)
- Marionette will no longer be enabled unless the
--marionette
command line argument or theMOZ_MARIONETTE
environment variable is specified. As such themarionette.enabled
preference is no longer used. With this change the state ofnavigator.webdriver
now correctly reflects the enabled state of Marionette (Firefox bug 1593343). - Fixed a bug where pointer actions other than
down
andup
inappropriately led to buttons being pressed (Firefox bug 1686361). - Fixed a race condition in
WebDriver:GetCurrentURL
that could have led the command to return the URL of the previously opened page, or even a hang in Marionette (Firefox bug 1664881).
Changes for add-on developers
url
can now be used to limit the properties for which thetabs.onUpdated
event is triggered (Firefox bug 1680279).
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