This article provides information about the changes in Firefox 80 that will affect developers. Firefox 80 was released on August 25, 2020.
Changes for web developers
Developer Tools
- You can now block and unblock network requests using the
:block
and:unblock
helper commands in the Web Console (bug 1546394). - When adding a class to an element in the Page Inspector's Rules pane, existing classes are suggested with autocomplete (Refer to bug 1492797).
- When the Debugger breaks on an exception, the tooltip in the source pane now shows a disclosure triangle that reveals a stack trace (bug 1643633).
- In the Network Monitor request list, a turtle icon is shown for "slow" requests that exceed a configurable threshold for the waiting time (bug 1648373).
HTML
No changes
CSS
- The standard, unprefixed
appearance
property is now supported; existing-moz-appearance
and-webkit-appearance
are now aliases of the unprefixed property (bug 1620467).
JavaScript
- The ECMAScript 2021
export * as namespace
syntax for theexport
statement is now supported (bug 1496852).
HTTP
- Previously, when the fullscreen directive was applied to an
<iframe>
(i.e. via theallow
attribute), it didn't work unless theallowfullscreen
attribute was also present This has now been fixed (bug 1608358).
APIs
DOM
- Web Animations API compositing operations are now enabled — see
KeyframeEffect.composite
andKeyframeEffect.iterationComposite
(bug 1652676).
WebGL
- The
KHR_parallel_shader_compile
WebGL extension is now supported (bug 1536674).
Removals
- The
outerHeight
andouterWidth
features ofWindow.open()
are no longer exposed to web content (bug 1623826).
WebAssembly
- Atomic operations are now allowed on non-shared memories (bug 1619196).
WebDriver conformance (Marionette)
- Using
WebDriver:NewWindow
to open a new tab no longer returns too early when running tests in headless mode (bug 1653281). - We removed the
name
argument forWebDriver:SwitchToWindow
— it is not supported for W3C-compatible mode, and shouldn't be used anymore (bug 1588424). - We've started to add Fission support for the following commands:
WebDriver:FindElement
,WebDriver:FindElements
,WebDriver:GetElementAttribute
,WebDriver:GetElementProperty
. - Known issue: Opening a new tab by using
WebDriver:NewWindow
, or via an arbitrary script that callswindow.open()
, now automatically switches to that new window (bug 1661495).
Changes for add-on developers
No changes
Older versions
- 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
- 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