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GitHub Repository: mohamedkhallouq/content
 Path: blob/main/files/en-us/mozilla/firefox/releases/35/index.md
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---
title: Firefox 35 for developers
slug: Mozilla/Firefox/Releases/35
---

{{FirefoxSidebar}}

Firefox 35 was released on January 13th, 2015. 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:

All devtools bugs fixed between Firefox 34 and Firefox 35.

CSS

  • The {{cssxref("mask-type")}} property has been activated by default (Firefox bug 1058519).

  • The {{cssxref("filter")}} property is now activated by default (Firefox bug 1057180).

  • The {{cssxref("@font-face")}} at-rule now supports WOFF2 fonts (Firefox bug 1064737).

  • The {{cssxref("symbols", "symbols()")}} functional notation is now supported (Firefox bug 966168).

  • The CSS Font Loading API has been implemented (Firefox bug 1028497).

  • Using -moz-appearance with the none value on a combobox now remove the dropdown button (Firefox bug 649849).

  • The property accessor element.style["css-property-name"] has been added to match other browsers (Firefox bug 958887).

HTML

  • The obsolete and non-conforming bottommargin, leftmargin, rightmargin and topmargin attributes of the {{HTMLElement("body")}} element have been activated in non-quirks mode (Firefox bug 95530).

JavaScript

  • The "temporal dead zone" for let declarations has been implemented. In conformance with ES2015 let semantics, the following situations now throw errors. See also this newsgroup announcement and Firefox bug 1001090.

    • Redeclaring existing variables or arguments using let within the same scope in function bodies is now a syntax error.

    • Using a variable declared using let in function bodies before the declaration is reached and evaluated is now a runtime error.

  • ES2015 {{jsxref("Global_Objects/Symbol", "Symbols")}} (only available in the Nightly channel) have been updated to conform with recent specification changes:

    • String(Symbol("1")) now no longer throws a {{jsxref("TypeError")}}; instead a string ("Symbol(1)") gets returned (Firefox bug 1058396).

  • The various TypedArray constructors now have as their [[Prototype]] a single function, denoted %TypedArray% in ES2015 (but otherwise not directly exposed). Each typed array prototype now inherits from %TypedArray%.prototype. (%TypedArray% and %TypedArray%.prototype inherit from Function.prototype and Object.prototype, respectively, so that typed array constructors and instances still have the properties found on those objects.) Typed array function properties now reside on %TypedArray%.prototype and work on any typed array. See TypedArray and Firefox bug 896116 for more information.

  • ES2015 semantics for prototype mutations using object literals have been implemented (Firefox bug 1061853).

    • Now only a single member notated as __proto__:value will mutate the [[Prototype]] in the object literal syntax.

    • Method members like __proto__() {} will not overwrite the [[Prototype]] anymore.

Interfaces/APIs/DOM

  • {{domxref("WorkerNavigator.language", "navigator.language")}} and {{domxref("WorkerNavigator.languages", "navigator.languages")}} are now available to workers on {{domxref("WorkerNavigator")}} (Firefox bug 925849).

  • The {{domxref("Element.closest()")}} method returns the closest ancestor of the current element (Firefox bug 1055533).

  • Experimental support for the {{domxref("CanvasRenderingContext2D.filter")}} property has been added behind the canvas.filters.enabled flag (Firefox bug 927892).

  • Our experimental implementation of Web Animations progresses with the landing of the Animation.target property. This always is behind the dom.animations-api.core.enabled pref, off by default (Firefox bug 1067701).

  • The {{domxref("Element.hasAttributes", "hasAttributes()")}} method has been moved from {{domxref("Node")}} to {{domxref("Element")}} as required by the spec (Firefox bug 1055773).

  • The crossOrigin reflected attribute of {{domxref("HTMLImageElement")}}, {{domxref("HTMLLinkElement")}}, {{domxref("HTMLMediaElement")}}, {{domxref("HTMLScriptElement")}}, and {{domxref("SVGScriptElement")}} only accepts valid values, and "" isn't, null has to be used instead (Firefox bug 880997).

  • The Resource Timing API has been activated by default (Firefox bug 1002855).

  • To match the spec, the first argument of {{domxref("Selection.containsNode()")}} cannot be null anymore (Firefox bug 1068058).

  • The new {{domxref("ImageCapture")}} API has been implemented: {{domxref("ImageCapture.takePhoto()")}} is available (Firefox bug 916643).

  • Non-HTTP {{domxref("XMLHttpRequest")}} requests now return 200 in case of success (instead of the erroneous 0) (Firefox bug 716491).

  • {{domxref("XMLHttpRequest.responseURL")}} has been adapted to the latest spec and doesn't include the fragment ('#xyz') of the URL, if relevant (Firefox bug 1073882).

  • The internal, non-standard, File.mozFullPath property is no more visible from content (Firefox bug 1048293).

  • The constructor of {{domxref("File")}} has been extended to match the specification (Firefox bug 1047483).

  • An experimental implementation of AbortablePromise, a promise that can be aborted by a different entity that the one who created it, has been added. It is prefixed with Moz and controlled by the dom.abortablepromise.enabled property, defaulting to false (Firefox bug 1035060).

  • The non-standard {{domxref("Navigator.mozIsLocallyAvailable")}} property has been removed (Firefox bug 1066826).

  • The preference network.websocket.enabled, true by default, has been removed; Websocket API cannot be deactivated anymore (Firefox bug 1091016).

  • The non-standard methods and properties of {{domxref("Crypto")}} have been removed (Firefox bug 1030963). Only methods and properties defined in the standard WebCrypto API are left.

  • Our experimental implementation of WebGL 2.0 is going forward!

    • The {{domxref("WebGL2RenderingContext.copyBufferSubData()")}} method has been implemented (Firefox bug 1048668).

MathML

  • The dtls OpenType feature (via the CSS {{cssxref("font-feature-settings")}} on the default stylesheet) is now applied automatically to MathML elements when positioning scripts over it (e.g. dotless i with mathematical hat).

SVG

No change.

Audio/Video

No change.

Network & Security

Changes for add-on and Mozilla developers

XUL & Add-ons

  • The private _getTabForBrowser() method on the <xul:tabbrowser> element has been deprecated. In its place, we've added a new, public, method called getTabForBrowser. This returns, predictably, the <xul:tab> element that contains the specified <xul:browser>.

  • Components.utils.now(), matching {{domxref("Performance.now()")}} has been implemented for non-window chrome code (Firefox bug 969490).

Add-on SDK

Highlights

  • Added access keys for context menu.

  • Removed isPrivateBrowsing from BrowserWindow.

  • Added toJSON method to URL instances.

Details

GitHub commits made between Firefox 34 and Firefox 35. This will not include any uplifts made after this release entered Aurora.

Bugs fixed between Firefox 34 and Firefox 35. This will not include any uplifts made after this release entered Aurora.

Older versions

{{Firefox_for_developers('34')}}