To test the latest developer features of Firefox, install Firefox Developer Edition Firefox 47 was released on June 6, 2016. This article lists key changes that are useful not only for web developers, but also Firefox and Gecko developers as well as add-on developers.
- User-agent spoofing from the Responsive mode
- Retaining paths panel in memory tool
- Service workers and Push API debugging
- Ability to filter Storage Inspector entries
- Console now detects incomplete input and switches multi-line mode
- Updated breakpoint style in Debugger
- Prevent panels from hiding automatically using the Browser Toolbox, to aid browser and add-on debugging
- Font inspector has been disabled by default
- 3D view has been removed
- Developer tools theme refresh
- Disable the Font Panel (Firefox bug 1247723).
- Support for the
::backdroppseudo-element has been added (Firefox bug 1064843).
- The case-insensitive modifier
[foo=bar i]) for attribute selectors has been implemented (Firefox bug 888190).
- An experimental implementation of CSS Mask Image properties landed. For the moment, this will only be available on Nightly versions of Firefox.y: shorthand version of
mask, as well as
mask-sizeare now available (Firefox bug 686281).
clip-pathproperty now experimentally supports
circle()on HTML elements (does not support inset() and path()), behind the pref
layout.css.clip-path-shapes.enabledthat defaults to
false(Firefox bug 1075457). Interpolation (and therefore animation) of these values is not yet supported.
- Our still experimental grid implementation has been updated:
display-modemedia feature is now supported (Firefox bug 1104916).
- The value
text-align-lasthas been renamed to
unsafe(Firefox bug 1250342).
- The new ES2017
Object.entries()methods have been implemented (Firefox bug 1232639).
- The deprecated, old Proxy API (
Proxy.createFunction) now presents a deprecation warning in the console and will be removed in a future version. Use the standard
Proxyobject instead (Firefox bug 892903).
- Support for the deprecated non-standard
replacehas been dropped in non-release builds (Firefox bug 1245801).
- As per the new ES2016 specification, the
Proxyenumerate trap for
for...instatements has been removed (Firefox bug 1246318).
Array.prototype.lastIndexOf()methods (and their
TypedArrayequivalents) have been updated to never return
-0as per the ECMAScript specification (Firefox bug 1242043).
DOM & HTML DOM
- The property
Document.scrollingElementhas been implemented behind the pref
dom.document.scrollingElement.enabledthat defaults to
false(Firefox bug 1153322).
Service Worker and related APIs
Request()constructor can now accept a referrer option in its init object (Firefox bug 1251448).
Request.referrerPolicyproperty is now supported (Firefox bug 1251872).
- Service workers and Push have been disabled in the Firefox 45 Extended Support Release (ESR) (Firefox bug 1232029).
- Support for the
RTCIceServerdictionary has been updated in keeping with revisions to the WebGL 1.0 specification by adding support for the credentialType property. This property is a string that specifies whether the credential is a password or a token. Currently, Firefox only supports
Cache.addAll()now raises a
TypeErrorexception if the response status is not in the
200range (Firefox bug 1244764).
- The App installation and management APIs (
navigator.mozApps.*) are no longer exposed to non-Firefox OS platforms (Firefox bug 1238576).
- Web Crypto API methods can now use the RSA-PSS cryptographic algorithm (Firefox bug 1191936).
- The Permissions API has had the
Permissions.revoke()method added (Firefox bug 1197461).
- The Browser API, which extends the functionality of
<iframe>s to allow the creation of frames for displaying web content using HTML — and was previously only available in Firefox OS — is now available to desktop chrome code too (Firefox bug 1238160).
- The Notification API's
requestPermission()method has been updated from a callback to a promised-based syntax (Firefox bug 1241278).
- The Fullscreen API has been updated to the latest spec and unprefixed. Some methods have been renamed or have seen their capitalization changed (Firefox bug 743198). Note that this is behind the
full-screen-api.unprefix.enabledpreference, defaulting to false (Firefox bug 1268749).
- Now WAV file with u-law compression encoding can be played(Firefox bug 851530).
- Widevine Content Decryption Module provided by Google Inc. is available via the Encrypted Media Extensions API for use with MP4 (only; see Firefox bug 1257716 for EME-with-WebM support) on Windows Vista and later and on Mac OS X enabling migration off Silverlight (Firefox bug 1265270).
- Firefox 46 for developers
- Firefox 45 for developers
- Firefox 44 for developers
- Firefox 43 for developers
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