This article provides information about the changes in Firefox 61 that will affect developers. Firefox 61 was released on June 26, 2018.
Changes for web developers
- The Accessibility Inspector has been implemented.
- The new-look Console UI has been enabled by default for the Browser Console & Browser Toolbox (bug 1362023/bug 1347127). The old UI has been removed.
- In the Network Monitor, clicking Open in New Tab in a
POSTrequest's context menu correctly resends the request with the expected
POSTparameters (bug 1407515).
- CSS variables now autocomplete with color swatches, allowing you to see exactly what color value is stored in each variable (bug 1451211).
- In addition, hovering over a CSS variable name brings up a tooltip showing what color value is stored in that variable (bug 1431949).
- The main toolbox's toolbar has been redesigned. Highlights are better responsiveness for narrow and wide viewports with a new overflow dropdown, cleaned up meatball menu, and sortable tabs to let you move up your most used panels (bug 1226272).
- The Network Monitor's toolbar now includes a dropdown menu providing easier access to the 'Copy All As HAR' and 'Save All As HAR' commands, as well as an 'Import...' option (bug 1403530).
- The Network Monitor's details pane now includes a Cache tab, which displays information about previously cached resources (bug 859051).
- The Network Monitor's main toolbar got redesigned to be more responsive on smaller viewports and visually aligned with the Console.
- The Network Monitor's main toolbar now includes a Throttling dropdown which was only available in the Responsive Design Mode before. It allows you to throttle your network speed to emulate various different network speed conditions (bug 1349559).
- The Browser Console now hides CSS errors by default for readability and performance reasons (bug 1452143).
- The Browser Console now includes a command to restart the browser. Use Ctrl + Alt + R (Windows, Linux) or Cmd + Alt + R (Mac) to restart the browser with the same tabs open as before the restart.
- DevTools' web extension APIs
devtools.network.onRequestFinished(bug 1311171) and
devtools.network.getHAR(bug 1311177) got implemented (enabling extensions like har-export-trigger).
- The Firebug theme got removed since the transition of Firebug users into DevTools is complete (bug 1378108).
- CSS parsing has been parallelized (bug 1346988).
- Support for
font-optical-sizinghas been enabled by default (bug 1447163).
grid-column-gapproperties have been renamed to
column-gap, as they are no longer grid-specific (bug 1398482). See Box alignment; Gaps between boxes for additional details. The old names have been kept as aliases for web compatibility purposes.
contentvalue is now supported (bug 1105111).
- Percentage values of
column-gapare now supported in CSS multi-column layout (bug 1398537).
- The CSS
:hostpseudo-class is now supported; this selects a custom element from inside its shadow DOM (bug 992245).
overflownow accepts two-value syntax (bug 1453148).
- Flex items that are sized according to their content are now sized using
fit-content(bug 1374540). See the
widthvalue definitions for more details of these values.
font-stylenow support additional values as defined by CSS Fonts level 4 (bug 1436048):
@font-facedescriptor equivalents of the three properties mentioned in the above entry also support the new syntax listed above, and additionally now support a two-value syntax allowing us to specify a range of descriptor values supported by a font-face (bug 1436061, bug 1436048).
textproperties have been added to the
SVGAElement) to be consistent with the HTML
<a>element (bug 1451823).
SVGTextPathElement) now supports the SVG2
sideattributes (bug 1446617 and bug 1446650).
SVGGeometryElementinterface is now supported for more elements and not just for the
<path>element (bug 1325320).
String.prototype.trimEnd()methods have been implemented (see bug 1434007).
trimRightremain as aliases for web compatibility reasons.
PerformanceServerTimingAPI has been implemented. It surfaces server-side metrics sent via the
Server-Timingheader (bug 1423495).
scriptsproperties have been moved from the
DOMTokenList.replace()now returns a boolean value to indicate whether the replacement occurred successfully, rather than void (bug 1444909).
- The Fetch API's
Request.credentialsproperty now defaults to
"same-origin"per the latest revision of the specification (bug 1394399).
Request.destinationproperty has been implemented (bug 1402892).
MutationObserverInit, no longer has
falseas the default value of all of its Boolean properties. Now, only
subtreehave default values (of
falsestill). The other properties have no default values (bug 973638).
- The Payment Request API method
PaymentRequest.show()now supports using a
Promiseto let the client side code provide updated payment details prior to activating the payment interface (bug 1441709).
The "Forget" button, available in Firefox's customization options, now clears service workers and their caches (bug 1252998).
Web Audio, Media and WebRTC
AudioContext()constructor now accepts an optional
optionsparameter of type
AudioContextOptions. This lets you configure the preferred latency and/or sample rate for the new context.
- Firefox now throws the correct exceptions when instantiation of an
Canvas and WebGL
CSSStyleRule.selectorTextproperty is now fully implemented and no longer read-only (bug 37468).
MediaListinterface implementation is now a little closer to the specification. It is not all the way there yet; for example, stringifier attributes haven't been implemented yet (bug 1455807).
- Firefox 61 and later no longer support using the FTP protocol (that is, URLs with the
"ftp://"scheme) to load subresources from within HTML content. FTP is still supported as a top-level URL entered directly into the URL bar or loaded as a standalone document (bug 1404744).
Removals from the web platform
Cmd/Ctrl + Shift + O no longer shows/hides the DevTools options panel — use F1 instead (bug 1409456).
@-moz-document has been disabled in content pages (bug 1422245).
lastModifiedDatehas been removed (bug 1458883).
Node.setUserData()methods have been removed from the platform completely (bug 749981).
Element.createShadowRoot()method has been removed. Use
Element.attachShadow()instead (bug 1453789).
MediaStreamoverload of the
URL.createObjectURL()method has been removed (bug 1454889).
- The deprecated (and never properly implemented)
.viewTargetproperty has been removed (bug 1455763).
- The following deprecated properties have been removed from
- The non-standard
SVGNumber()constructor has been removed (bug 1455940).
Changes for add-on and Mozilla developers
- Autocomplete popups are now themeable (bug 1417883).
tabs.onUpdatednow has a filter template (bug 1329507).
- The default document colors can now be overridden, using
- tabs.query has been optimized with the implementation of some useful search/filter option parameters (bug 1445316).
- You can now use
about:addonspreferences page (bug 1382953).
- You can now force web pages to use system fonts instead of the fonts they specify using the
browserSettings.useDocumentFontsproperty (bug 1400805).
- You can now cause browser search autocomplete suggestions to automatically open in a new tab rather than the current tab using the
browserSettings.openUrlbarResultsInNewTabsproperty (bug 1432645).
toolbar_field_bordertheme manifest properties now also apply to the findbar (bug 1418605).
sidebarAction.setIcon(), you can now specify a
windowIdso that the features will be set/got only for a specific window (bug 1390464).
tabs.show()are now enabled by default (bug 1455040).
- The first time an extension hides a tab, the browser will tell the user that the tab is being hidden, show them how they can access the hidden tab, and give them the option of disabling the extension instead (bug 1438363).
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