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Firefox 45 for developers 编辑

To test the latest developer features of Firefox,
install Firefox Developer Edition Firefox 45 was released on March 8, 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.

Changes for Web developers

Developer Tools

HTML

Content Security Policy can now be set directly on the <meta> element (bug 663570).
The attribute referrer has been renamed referrerpolicy on <img>, <area>, <a>, and <iframe> (bug 1187357).
Changes in the viewport, or a resize, now trigger the reselection of responsive images for <img srcset> (bug 1166138).

CSS

word-spacing now allows percentage values (bug 1038663).
Our implementation of CSS Grids has been improved and is no more considered experimental; it is now activated by default in nightly and developer edition, but not for beta and release (bug 1000592):
- Gutters, that is the grid-column-gap, grid-row-gap, and grid-gap properties are now supported (bug 1176792).
- The implied minimum size of grid Items, that is the special min-width and min-height auto behavior has been implemented (bug 1176775).
- align-self and justify-self are now supported on grid layouts (bug 1151213).
- align-content and justify-content are now supported on grid layouts (bug 1151214).
- Resolved value of grid-template-columns,grid-template-rows in px units (bug 978212).
- The related feature display: contents has been supported since Firefox 37
Implement full support for CSS Box Alignment for CSS Grid, support the missing values: start, end, self-start, self-end, left, right,last-baseline,space-evenly (bug 1176782). CSS Box Alignment currently applies only to CSS Flexbox and CSS Grid.
[css-grid][css-flexbox] Implement grid/flex layout for <fieldset> (bug 1230207).
The inline-start and inline-end values have been added to float and clear (bug 1122918). They are enabled by default on Nightly and Aurora (Dev edition), as well as on Firefox OS; to activate it on a release or beta version, you need to flip the layout.css.float-logical-values.enabled to true.
The text-emphasis, text-emphasis-style, text-emphasis-color, and text-emphasis-position have been implemented; they are disabled by default (set layout.css.text-emphasis.enabled to true to activate them (bug 1040668).
Several -webkit prefixed properties and values have been added for web compatibility, behind the preference layout.css.prefixes.webkit, defaulting to false:
- Added -webkit-backface-visibility, -webkit-perspective and -webkit-perspective-origin for web compatibility, behind the preference layout.css.prefixes.webkit, defaulting to false (bug 1179444).

JavaScript

ES2015 Classes are now enabled by default (bug 1197932).
Expression closures are deprecated and will now present a warning in the console (bug 995610).
String.prototype.replace does not restore RegExp static properties after executing function parameter anymore (bug 1226936).
Math.random() has been updated to the better XorShift128+ algorithm (bug 322529).

Interfaces/APIs/DOM

DOM & HTML DOM

For compatibility, the non-standard property Node.innerText has been implemented (bug 264412).
The HTMLImageElement.srcset attribute now reacts to resize/viewport changes (bug 1166138).
Element.getAttributeNames() has been implemented (bug 1228634).

WebGL

Our implementation of WebGL 2 has been extended:

Support of programs and shaders has been added (bug 1048743).
Support for uniforms and attributes has been added (bug 1048745).
Framebuffer objects have been implemented (bug 1048732).
Renderbuffer objects have been implemented (bug 1048733).

IndexedDB

No change.

Service Workers

Clients.get() and FetchEvent.clientId have been implemented (bug 1222464.)
Clients.openWindow() has been implemented (bug 1172870.)
The options object that can be passed as a parameter when invoking Clients.matchAll() can now include an includeUncontrolled property. This is a Boolean — if set to true, the matching operation will return all service worker clients who share the same origin as the current service worker. Otherwise, it returns only the service worker clients controlled by the current service worker. The default is false.

WebRTC

No change.

New APIs

No change.

Miscellaneous

Web Speech Synthesis API has been implemented on Firefox Desktop (bug 1003439).
The Window.onstorage event handler property has been added.
The interface ComputedTiming have been added to our experimental implementation of Web Animations API (bug 1108055).
The Document.onselectionchange event handler property has been added (bug 1231193).
After removing a video track from a media stream by calling MediaStream.removeTrack() you can nowadd another video track later using MediaStream.addTrack() and have it played (bug 1223696).

MathML

No change.

SVG

SVG stroke hit-testing is buggy when cairo is the Moz2D backend (bug 676001).
Unable to interact with elements who have large transform / translate values (bug 1217012).

Audio/Video

Fixed: Regression (since Firefox 41) whereby audio playback was stuttering due to duration time rounding errors (bug 1222866.)

HTTP

The jar: protocol has been disabled by default when accessed from Web content; you may enable this if necessary by setting the network.jar.block-remote-files preference to false (bug 1215235).

Security

A Content-Security-Policy can now be specified using a <meta> element (bug 663570).
Support of the child-src CSP policy directive has been implemented (bug 1045891).
EV certificates with a validity greater than 27 months are now considered and handled as DV certificates (bug 1222903).

Changes for add-on and Mozilla developers

Interfaces

No change.

XUL

Tab Groups have been removed.

JavaScript code modules

No change.

XPCOM

No change.

Search plugins

Starting in Firefox 45, search plugins located in the user's profile's searchplugins directory are no longer automatically loaded on startup. Instead, a list of user-installed plugins is maintained and only those plugins are loaded. In effect, this means that the only ways to install new search plugins are for the user to do so in the Firefox UX (via OpenSearch discovery, for instance) or for an add-on to install it. Also, when a new search plugin is installed, more information is recorded about where it came from, for future use by profile debugging and cleaning tools.

Other

WebIDL constructors could be called without the new operator in chrome context. Now such code will raise a TypeError as in Web content since Firefox 30. For example, var req = XMLHttpRequest(); needs to be var req = new XMLHttpRequest();.