Site Compatibility for Firefox 26




Firefox 26 Aurora (pre-Beta) will be released on . While it has been developed to maintain compatibility as much as possible, the new version includes some changes affecting backward compatibility aimed at improving interoperability with the other browsers or following the latest Web standards. Here's the list of such changes — hope this helps whenever you test your sites or applications.

This article only explains the changes that may affect backward compatibility for Websites. For the other new features and changes, please read the following documents:

This list may be updated until the release of the final version on , so please check back later. Follow @MozWebCompat on Twitter for further updates.

The non-standard -moz-text-blink property has been removed. Instead, the standard, still prefixed text-decoration-line property now takes blink as a valid value. Actually it doesn't blink any content on Firefox though, from the perspective of accessibility. Note that the blink effect with text-decoration:blink has been dropped with Firefox 23.


type 属性不是 image 的 HTMLInputElement 元素的 width 和 height 属性会返回 0

Previously, the width and height properties of an <input> returned the dimension of the element. To comply with the spec, those properties now return 0 if the type property is not image.

Setting document.domain in a sandboxed iframe is no longer allowed

Setting the document.domain property on a page embedded in an <iframe> with the sandbox attribute will throw a security error from now on.

元素的 id 改变后,旧 id 不再是 window 对象的属性

An element with id is accessible through window.<id>. Previously, the DOM object remained on window even after the id of the element is programmatically changed. This odd behavior has been fixed with Firefox 26. The document.getElementById method, which is recommended to use in general, is not affected by this change.

MessageEvent has been updated

The MessageEvent interface has been updated to comply with the latest spec. The initMessageEvent method has been removed while the interface is now a constructor.

HTMLCanvasElement.mozGetAsFile has been deprecated

The non-standard mozGetAsFile method on the HTMLCanvasElement interface is now deprecated and will be removed soon. The standard toBlob method can be used instead.

UserDataHandler has been removed

The deprecated UserDataHandler interface has been removed. The Node.setUserData and Node.getUserData methods have already been removed with Firefox 22.

The following methods on the XBL DOM Interface have been removed from the Document interface: getAnonymousNodes, getAnonymousElementByAttribute, getBindingParent and loadBindingDocument.

Various non-standard interfaces have been removed

As part of the ongoing effort to standardize global objects, the following non-standard interfaces have been removed: ChromeWindow, StorageIndexedDB, XULButtonElement, XULCheckboxElement, XULCommandDispatcher, XULCommandEvent, XULControlElement, XULDocument, XULElement, XULLabeledControlElement and XULPopupElement.


The reserved words are no longer allowed as function names

The reserved words cannot be used for function names. Starting with Firefox 26, such a usage will throw a SyntaxError. For example, function delete() { ... } is illegal.


All plug-ins except Flash are now defaulted to Click-to-Play

Starting with Firefox 26, plug-ins require user interaction to be activated. With the exception of the popular Adobe Flash Player, all plug-in content embedded in a Web page is now disabled by default and enabled by user's click. This change has been made in order to improve security and performance of the browser. See the Mozilla Security Blog for details. Web developers are encouraged to leverage modern Web technologies, including HTML5, to provide richer user experience.