Firefox 80 for developers
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 (Firefox bug 1546394). - When adding a class to an element in the Page Inspector's Rules pane, existing classes are suggested with autocomplete (Refer to Firefox 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 (Firefox 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 (Firefox 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 (Firefox bug 1620467).
JavaScript
- The ECMAScript 2021
export * as namespace
syntax for theexport
statement is now supported (Firefox 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 (Firefox bug 1608358).
APIs
DOM
- Web Animations API compositing operations are now enabled — see
KeyframeEffect.composite
andKeyframeEffect.iterationComposite
(Firefox bug 1652676).
Removals
- The
outerHeight
andouterWidth
features ofWindow.open()
are no longer exposed to web content (Firefox bug 1623826).
WebAssembly
- Atomic operations are now allowed on non-shared memories (Firefox bug 1619196).
WebDriver conformance (Marionette)
- Using
WebDriver:NewWindow
to open a new tab no longer returns too early when running tests in headless mode (Firefox bug 1653281). - We removed the
name
argument forWebDriver:SwitchToWindow
— it is not supported for W3C-compatible mode, and shouldn't be used anymore (Firefox 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 (Firefox 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