This article provides information about the changes in Firefox 77 that will affect developers. Firefox 77 was released on June 2, 2020.
- Mozilla Firefox Developer Version Download
- Download Mozilla Firefox Developer
- Mozilla Firefox Developer Edition 64 Bit Offline Installer
- Mozilla Firefox Developer Edition Vs Regular
- The browser we know as Firefox started as Phoenix 0.1 in Sept 2002. Due to Phoenix Bios existing Mozilla changed name to Firebird for 0.6 to 0.7. Then due to the open source Firebird SQL already being around for a bit Mozilla decided to not have confusion between the two and changed it to Firefox starting at Release version 0.8 to present.
- 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.
Mozilla Firefox Developer Version Download
Firefox Developer Edition, also called Firefox Quantum, allows users to get their hands on the latest features and development tools which will eventually find their way into the mainstream, stable. Get the latest features, fast performance, and the development tools you need to build for the open web. Firefox Developer Edition — English (US) Windows 64-bit. Windows 64-bit MSI. Windows ARM64/AArch64. Windows 32-bit MSI.
The developer release will install alongside a standard Firefox Portable install in a FirefoxPortableDeveloper directory. Note that PortableApps.com will release one version for each major version (example: 78b1 but not 78b2). For updates within each major release, use the internal updater.
See also the accompanying hacks post — New in Firefox 77: DevTool improvements and web platform updates.
Changes for web developers
Developer tools
- Firefox Developer Edition offers a Compatibility panel in the Page Inspector, to show the browsers supported by the CSS properties used on the page. (bug 1625134)
- The Debugger has a Settings menu in its toolbar; the only menu option (yet) is Disable JavaScript. (bug 1630957)
- The Network Monitor toolbar has an Actions menu for managing log data (bug 1459175):
- Persist Logs
- Import HAR File
- Save All as HAR
- Copy All as HAR
- The Request Blocking panel of the Network Monitor has a context menu for enabling, disabling or removing all request block items. (bug 1588076)
- If you change the selected source line in the Debugger by clicking a frame in the Call Stack, and then click Step over (F10), the debugger executes until reaching the line following the newly-selected line (disregarding whatever line the debugger originally stopped at). (bug 1630642)
- You can set a watchpoint that pauses execution when a value is either read or assigned ('get or set'), as well as just read ('get') or just assigned ('set'). (bug 1580585
HTML
Download Mozilla Firefox Developer
- Firefox now displays the label value on an
<option>
element when the element's content is empty. (bug 40545)
SVG
- Firefox now supports the
transform-origin
presentation attribute (bug 1581691).
JavaScript
String.prototype.replaceAll()
is now supported (bug 1608168).
APIs
IndexedDB
- The
IDBCursor.request
property has been implemented (bug 1536540).
WebDriver conformance (Marionette)
- Certain commands could have caused a hang of Marionette when the currently selected top-level browsing context gets removed, eg. closing the window by a click (bug 1619481).
- Known issue: Because of changes in Firefox 77 an open user prompt could be closed too early when navigating away from the current page. This problem will be fixed in Firefox 78 (bug 1631362).
Changes for add-on developers
API changes
tabs.goBack
andtabs.goForward
are now supported. (bug 1603796)browsingData.remove
with typeserviceWorkers
andindexedDB
now supports deleting by hostname. (bug 1632990 and bug 1551301)- The
tabs.duplicate
API now supportsduplicateProperties
, enabling the position and active status of a duplicated tab to be specified. (bug 1560218) - The
permissions
API eventspermissions.onAdded
andpermissions.onRemoved
are now supported. (bug 1444294) - Multiple
Content-Security-Policy
header changes requested inwebRequest.onHeadersReceived
are merged. (bug 1462989)
Manifest changes
- The following permissions are now optional, they can be specified in the
optional_permissions
manifest key and requested using thepermissions
API:browsingData
(bug 1630417),pkcs11
(bug 1630418),proxy
(bug 1548011), andsessions
(bug 1630414).
Other
- Use of the
unlimitedStorage
permission no longer results in a prompt during extension installation or update. See Requesting the right permissions for more information. (bug 1630413) - Changes related to SameSite cookies mean that when setting host permissions to bypass tracking protection for extension pages hosts must be specified as a full domain or with wildcards. However, for Content scripts tracking protection can only be bypassed for hosts specified with a full domain.