Firefox 45 for developers
=========================

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

Highlights:

* Full-text search in the Page Inspector
* Heap snapshot diffing in the Memory tool
* DomContentLoaded and load events shown in the Network Monitor
* Animation inspector improvements

All devtools bugs fixed between Firefox 43 and Firefox 44.

### HTML

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

* `word-spacing` now allows percentage values (Firefox 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 (Firefox bug 1000592):
    + Gutters, that is the `grid-column-gap`, `grid-row-gap`, and `grid-gap` properties are now supported (Firefox bug 1176792).
    + The implied minimum size of grid Items, that is the special `min-width` and `min-height` `auto` behavior has been implemented (Firefox bug 1176775).
    + `align-self` and `justify-self` are now supported on grid layouts (Firefox bug 1151213).
    + `align-content` and `justify-content` are now supported on grid layouts (Firefox bug 1151214).
    + Resolved value of grid-template-columns,grid-template-rows in px units (Firefox 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` (Firefox bug 1176782). CSS Box Alignment currently applies only to CSS Flexbox and CSS Grid.
* [css-grid][css-flexbox] Implement grid/flex layout for <fieldset> (Firefox bug 1230207).
* The `inline-start` and `inline-end` values have been added to `float` and `clear` (Firefox 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 (Firefox 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` (Firefox bug 1179444).
### JavaScript

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

#### DOM & HTML DOM

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

#### WebGL

Our implementation of WebGL 2 has been extended:

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

#### IndexedDB

*No change.*

#### Service Workers

* `Clients.get()` and `FetchEvent.clientId` have been implemented (Firefox bug 1222464.)
* `Clients.openWindow()` has been implemented (Firefox 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 value — 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 (Firefox bug 1003439).
* The `storage` event has been added.
* The interface `ComputedTiming` have been added to our experimental implementation of Web Animations API (Firefox bug 1108055).
* The `Document.onselectionchange` event handler property has been added (Firefox bug 1231193).
* After removing a video track from a media stream by calling `MediaStream.removeTrack()` you can now add another video track later using `MediaStream.addTrack()` and have it played (Firefox bug 1223696).
### MathML

*No change.*

### SVG

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

* Fixed: Regression (since Firefox 41) whereby audio playback was stuttering due to duration time rounding errors (Firefox 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` (Firefox bug 1215235).
Security
--------

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

* Firefox 44 for developers
* Firefox 43 for developers
* Firefox 42 for developers
* Firefox 41 for developers
* Firefox 40 for developers
* Firefox 39 for developers
* Firefox 38 for developers
* Firefox 37 for developers
* Firefox 36 for developers
* Firefox 35 for developers
* Firefox 34 for developers
* Firefox 33 for developers
* Firefox 32 for developers
* Firefox 31 for developers
* Firefox 30 for developers
* Firefox 29 for developers
* Firefox 28 for developers
* Firefox 27 for developers
* Firefox 26 for developers
* Firefox 25 for developers
* Firefox 24 for developers
* Firefox 23 for developers
* Firefox 22 for developers
* Firefox 21 for developers
* Firefox 20 for developers
* Firefox 19 for developers
* Firefox 18 for developers
* Firefox 17 for developers
* Firefox 16 for developers
* Firefox 15 for developers
* Firefox 14 for developers