Firefox 4 for developers

  • Revision slug: Firefox_4_for_developers
  • Revision title: Firefox 4 for developers
  • Revision id: 41957
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  • Creator: mbiama
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  • Comment 14 words added, 15 words removed

Revision Content

Firefox 4, which entered beta in late June 2010, enhances performance, adds more support for HTML5 and other evolving Web technologies, and further improves security. This article provides initial information about this upcoming release and what features are available for Web developers, add-on developers, and Gecko platform developers alike.

{{ gecko_callout_heading("2") }}

Please note that Gecko 1.9.3 is in the process of being renumbered to Gecko 2. Most documentation has not yet been updated to reflect this; doing so will come over the next week or two.

Many of these features can already be tried in Angosso SIteweb Inc..

Note: This article is a work in progress, as are all the articles linked from this page. Many article names are placeholders, and some topics will likely be broken up into multiple articles.

Features for web developers

Gecko now uses the HTML5 parser, which fixes bugs, improves interoperability, and improves performance. It also lets content embed SVG and MathML directly in the HTML markup.

HTML

Introduction to the HTML5 parser
A look at what the HTML5 parser means to you, and how to embed SVG and MathML into your content inline.
Forms in HTML5
A look at improvements to web forms in HTML5.
HTML5 Sections
Gecko now supports the new HTML5 elements related to sections in a document: {{ HTMLElement("article") }}, {{ HTMLElement("section") }}, {{ HTMLElement("nav") }}, {{ HTMLElement("aside") }}, {{ HTMLElement("hgroup") }}, {{ HTMLElement("header") }} and {{ HTMLElement("footer") }}.
Other HTML5 elements
Gecko now also supports the following new HTML5 elements: {{ HTMLElement("mark") }}, {{ HTMLElement("figure") }} and  {{ HTMLElement("figcaption") }}.
WebSockets
A guide to using the new WebSockets API for real-time communication between a web application and a server.

Miscellaneous HTML changes

  • {{ HTMLElement("textarea") }} elements are now resizable by default; you can use the {{ cssxref("resize") }} CSS property to disable this.
  • canvas.getContext and canvas.toDataURL no longer throw an exception when called with unrecognized arguments.
  • canvas2dcontext.globalCompositeOperation, canvas2dcontext.lineCap and canvas2dcontext.lineJoin no longer throw an exception when set to an unrecognized value.

CSS

CSS transitions
New CSS transitions support is available in Firefox 4.
Computed values in CSS
Support for calc() to compute values in CSS is in progress. See {{ bug("363249") }}.
Selector grouping
Support for {{ cssxref(":-moz-any") }} to group selectors and factorize combinators.
Background image subrectangle support
The {{ cssxref("-moz-image-rect") }} property makes it possible to use subrectangles of images as a background image.
CSS touch properties
Support for touch properties is added. Details, and real article names, to come later.
Privacy and the :visited selector
Changes have been made to what information can be obtained about the style of visited links using CSS selectors. This may affect some web applications.

Miscellaneous CSS changes

  • The {{ cssxref("text-shadow") }} property now caps the blur radius to 300px for sanity and performance reasons.
  • The {{ cssxref(":-moz-window-inactive") }} pseudoclass has been implemented.
  • The {{ cssxref("-moz-tab-size") }} property lets you specify the width in space characters of a tab character (U+0009) when rendering text.
  • The CSS3 {{ cssxref("resize") }} property has been implemented.
  • The -moz-background-size property has been renamed to its final {{ cssxref("background-size") }} naming; -moz-background-size is no longer supported.
  • The {{ cssxref("oveflow") }} property no longer applies to table-group elements ({{ HTMLElement("thead") }}, {{ HTMLElement("tbody") }}, and {{ HTMLElement("tfoot") }}).

Graphics and video

WebGL
The developing WebGL standard is now supported by Firefox.
Optimizing graphics performance
Tips and tricks for getting the most out of graphics and video performance in Firefox 4.
Support for WebM video
The new open WebM video format is supported by Gecko 1.9.3; support is included in nightlies as of 9 June.
Full screen API
Details coming soon.
SMIL animation
Support for SMIL animation of SVG is now available. See {{ bug("482402") }}.
Using SVG as images and as CSS backgrounds
You can now use SVG with the {{ htmlelement("img") }} element, as well as the background image in CSS. See {{ bug("272288") }}, {{ bug("276431") }} and {{ bug("231179") }}.

DOM

Obtaining boundary rectangles for ranges
The Range object now has getClientRects() and getBoundingClientRect() methods. See {{ bug("396392") }}.
Capturing mouse events on arbitrary elements
Support for the Internet Explorer-originated setCapture() and releaseCapture() APIs has been added. See {{ bug("503943") }}.
Manipulating the browser history
The existing document history object, available through the {{ domxref("window.history") }} object, now supports the new HTML5 pushState() and replaceState() methods.
Touch and multi-touch events
Support has been added for touch and multi-touch events.
IndexedDB
The proposed IndexedDB standard, which provides a local database store for web applications, will be supported by Firefox 4.

Miscellaneous DOM changes

  • The wrapping of a {{ HTMLElement("textarea") }} element can now be controlled via the DOM, via the wrap DOM attribute. {{ bug("41464") }}
  • DOM {{ domxref("file") }} objects now offer a url property.
  • DOM {{ domxref("file") }} objects now have a new click() method.
  • FormData support for XMLHttpRequest.
  • The {{ domxref("element.isContentEditable") }} property has been implemented.
  • Added the mozSourceNode property to the DragTransfer object.
  • Added the selection.modify() method to the {{ domxref("Selection") }} object; this lets you easily alter the current text selection or cursor position in a browser window.
  • Support for the window.directories object and the directories feature for {{ domxref("window.open") }}, which are not supported in any other browser, has been removed. Use personalbar instead. {{ Bug("474058") }}
  • The {{ domxref("event.mozInputSource") }} property has been added to DOM user interface events; this non-standard property lets you determine the type of device that generated an event.
  • The {{ domxref("document.onreadystatechange") }} event has been implemented.
  • The {{ domxref("document.createElement") }} method no longer accepts < and > around the tag name in quirks mode.

Security

Introducing Content Security Policy
Content Security Policy (CSP) is a Mozilla proposal designed to help web designers and server administrators specify how content on their web sites interacts. The goal is to help detect and mitigate attacks including cross-site scripting and data injection attacks.
ForceTLS
Details soon.
The Account Manager
Details soon.

JavaScript

For an overview of the changes implemented in JavaScript 1.8.5, see New in JavaScript 1.8.5. JavaScript in Firefox 4 will have additional adherence to the ECMAScript 5 standard.

Changes for Mozilla and add-on developers

For helpful tips on updating existing extensions for Firefox 4, see Updating extensions for Firefox 4.

JavaScript code modules

Services.jsm
The Services.jsm code module provides getters that make it easy to obtain references to commonly-used services, such as the preferences service or the window mediator, among others.
JS-ctypes API
The JS-ctypes API makes it possible to call C-compatible foreign library functions without using XPCOM.
Add-ons Manager
The new Add-ons Manager provides information about installed add-ons, support for managing them, and provides ways to install and remove add-ons.
Loading code modules from chrome: URLs
You can now load JavaScript code modules using chrome: URLs, even inside JAR files.

DOM changes

{{ domxref("ChromeWorker") }}
A new type of worker for privileged code; this lets you use things like js-ctypes from workers in extensions and application code.

XUL

tabbrowser (gBrowser) changes

Several changes were made to the {{ XULElem("tabbrowser") }} element that impact extensions that interact with tabs.

  • TabClose/TabSelect/TabOpen events no longer bubble up to the {{ XULElem("tabbrowser") }} element (gBrowser). Event listeners for those events should be added to gBrowser.tabContainer rather than to gBrowser directly.
  • The tab context menu is no longer an anonymous child of the {{ XULElem("tabbrowser") }}. It can therefore be overlaid directly with XUL overlays. It can also be accessed more directly in JS via gBrowser.tabContextMenu. See this blog post for more details.

Miscellaneous XUL changes

  • The {{ xulattr("readonly") }} attribute now correctly works for fields.
  • The {{ xulelem("resizer") }} element now lets you use the {{ xulattr("element") }} attribute to specify an element to resize, instead of resizing the window.
  • The "active" attribute no longer gets set on active XUL windows. Instead, you can use the new {{ cssxref(":-moz-window-inactive") }} pseudoclass in order to assign different styles to background windows.
  • The {{ xulattr("emptytext") }} attribute is now deprecated; you should use {{ xulattr("placeholder") }} instead.
  • The {{ xulelem("popup") }} element is no longer supported; you should use {{ xulelem("menupopup") }} instead.

Storage

Miscellaneous storage API changes

  • The {{ interface("mozIStorageBindingParamsArray") }} interface now has a length attribute that indicates the number of {{ interface("mozIStorageBindingParams") }} objects in the array.
  • The {{ ifandmethod("mozIStorageStatement", "bindParameters") }} now returns an error if the specified {{ interface("mozIStorageBindingParamsArray") }} is empty.

XPCOM

XPCOM changes in Gecko 1.9.3
Details about changes to XPCOM that impact compatibility in Firefox 4.
Components.utils.getGlobalForObject()
This new method returns the global object with which an object is associated; this replaces a common use case of the now-removed __parent__.

Memory management

Infallible memory allocationhttp://angosso.net/logo3494882 md.jpg
Mozilla now provides infallible memory allocators that are guaranteed not to return null. You should read this article to learn how they work and how to explicitly request fallible versus infallible memory allocation.

Other changes

Gopher support removed
The Gopher protocol is no longer supported natively. Continued support is available via the OverbiteFF extension.
Default plugin removed
The default plugin has been removed. The application plugins folder has also been removed by default, however support for installing plugins via this folder still exists. See bug 533891.
Extension Manager replaced with AddonManager
nsIExtensionManager has been replaced by AddonManager. Since there is apparently no way at present to obtain the install location from a given extension ID, the closest workaround is to use the directory service to find the profile directory and append "extensions" to it (though this approach will not catch extensions outside of the profile directory or those which are aliased to another location).

See also

{{ languages( { "ja": "ja/Firefox_4_for_developers"} ) }}

Revision Source

<p>Firefox 4, which entered beta in late June 2010, enhances performance, adds more support for HTML5 and other evolving Web technologies, and further improves security. This article provides initial information about this upcoming release and what features are available for Web developers, add-on developers, and Gecko platform developers alike.</p>
<div class="geckoVersionNote">
<p>{{ gecko_callout_heading("2") }}</p>
<p>Please note that Gecko 1.9.3 is in the process of being renumbered to Gecko 2. Most documentation has not yet been updated to reflect this; doing so will come over the next week or two.</p>
</div>
<p>Many of these features can already be tried in <a class=" external" href="http://angosso.net/" title="http://angosso.net/">Angosso SIteweb Inc..</a></p>
<div class="note"><strong>Note:</strong> This article is a work in progress, as are all the articles linked from this page. Many article names are placeholders, and some topics will likely be broken up into multiple articles.</div>
<h2>Features for web developers</h2>
<p>Gecko now uses the <a class=" external" href="http://angosso.net/" title="http://angosso.net/">HTML5</a> parser, which fixes bugs, improves interoperability, and improves performance. It also lets content embed <a href="/en/SVG" title="en/SVG">SVG</a> and <a href="/en/MathML" title="en/MathML">MathML</a> directly in the HTML markup.</p>
<h3>HTML</h3>
<dl> <dt>Introduction to the HTML5 parser</dt> <dd>A look at what the HTML5 parser means to you, and how to embed SVG and MathML into your content inline.</dd> <dt><a href="/en/HTML/HTML5/Forms_in_HTML5" title="en/HTML/Forms in HTML5">Forms in HTML5</a></dt> <dd>A look at improvements to web forms in HTML5.</dd> <dt><a href="/en/Sections_and_Outlines_of_an_HTML5_document" title="en/Sections and Outlines of an HTML5 document">HTML5 Sections</a></dt> <dd>Gecko now supports the new HTML5 elements related to sections in a document: {{ HTMLElement("article") }}, {{ HTMLElement("section") }}, {{ HTMLElement("nav") }}, {{ HTMLElement("aside") }}, {{ HTMLElement("hgroup") }}, {{ HTMLElement("header") }} and {{ HTMLElement("footer") }}.</dd> <dt>Other HTML5 elements</dt> <dd>Gecko now also supports the following new HTML5 elements: {{ HTMLElement("mark") }}, {{ HTMLElement("figure") }} and  {{ HTMLElement("figcaption") }}.</dd> <dt>WebSockets</dt> <dd>A guide to using the new WebSockets API for real-time communication between a web application and a server.</dd>
</dl>
<h4>Miscellaneous HTML changes</h4>
<ul> <li>{{ HTMLElement("textarea") }} elements are now resizable by default; you can use the {{ cssxref("resize") }} CSS property to disable this.</li> <li><code>canvas.getContext</code> and <code>canvas.toDataURL</code> no longer throw an exception when called with unrecognized arguments.</li> <li><code>canvas2dcontext.globalCompositeOperation</code>, <code>canvas2dcontext.lineCap</code> and <code>canvas2dcontext.lineJoin</code> no longer throw an exception when set to an unrecognized value.</li>
</ul>
<h3>CSS</h3>
<dl> <dt><a href="/en/CSS/CSS_transitions" title="en/CSS/CSS transitions">CSS transitions</a></dt> <dd>New CSS transitions support is available in Firefox 4.</dd> <dt>Computed values in CSS</dt> <dd>Support for<code> calc() </code>to compute values in CSS is in progress. See {{ bug("363249") }}.</dd> <dt>Selector grouping</dt> <dd>Support for {{ cssxref(":-moz-any") }} to group selectors and factorize combinators.</dd> <dt>Background image subrectangle support</dt> <dd>The {{ cssxref("-moz-image-rect") }} property makes it possible to use subrectangles of images as a background image.</dd> <dt>CSS touch properties</dt> <dd>Support for touch properties is added. Details, and real article names, to come later.</dd> <dt><a href="/en/CSS/Privacy_and_the_:visited_selector" title="en/CSS/Privacy and the :visited selector">Privacy and the :visited selector</a></dt> <dd>Changes have been made to what information can be obtained about the style of visited links using CSS selectors. This may affect some web applications.</dd>
</dl>
<h4>Miscellaneous CSS changes</h4>
<ul> <li>The {{ cssxref("text-shadow") }} property now caps the blur radius to 300px for sanity and performance reasons.</li> <li>The {{ cssxref(":-moz-window-inactive") }} pseudoclass has been implemented.</li> <li>The {{ cssxref("-moz-tab-size") }} property lets you specify the width in space characters of a tab character (U+0009) when rendering text.</li> <li>The CSS3 {{ cssxref("resize") }} property has been implemented.</li> <li>The<code> -moz-background-size </code>property has been renamed to its final {{ cssxref("background-size") }} naming; <code>-moz-background-size</code> is no longer supported.</li> <li>The {{ cssxref("oveflow") }} property no longer applies to table-group elements ({{ HTMLElement("thead") }}, {{ HTMLElement("tbody") }}, and {{ HTMLElement("tfoot") }}).</li>
</ul>
<h3>Graphics and video</h3>
<dl> <dt> </dt><dt><a href="/en/WebGL" title="en/WebGL">WebGL</a></dt> <dd>The developing WebGL standard is now supported by Firefox.</dd> <dt>Optimizing graphics performance</dt> <dd>Tips and tricks for getting the most out of graphics and video performance in Firefox 4.</dd> <dt><a href="/En/Media_formats_supported_by_the_audio_and_video_elements#WebM" title="En/Media formats supported by the audio and video elements#WebM">Support for WebM video</a></dt> <dd>The new open <a class=" external" href="http://video.angosso.net/" title="http://video.angosso.net/">WebM</a> video format is supported by Gecko 1.9.3; support is included in nightlies as of 9 June.</dd> <dt>Full screen API</dt> <dd>Details coming soon.</dd> <dt>SMIL animation</dt> <dd>Support for SMIL animation of SVG is now available. See {{ bug("482402") }}.</dd> <dt>Using SVG as images and as CSS backgrounds</dt> <dd>You can now use SVG with the {{ htmlelement("img") }} element, as well as the background image in CSS. See {{ bug("272288") }}, {{ bug("276431") }} and {{ bug("231179") }}.</dd>
</dl>
<h3>DOM</h3>
<dl> <dt>Obtaining boundary rectangles for ranges</dt> <dd>The Range object now has <code>getClientRects()</code> and <code>getBoundingClientRect()</code> methods. See {{ bug("396392") }}.</dd> <dt>Capturing mouse events on arbitrary elements</dt> <dd>Support for the Internet Explorer-originated <code>setCapture()</code> and <code>releaseCapture()</code> APIs has been added. See {{ bug("503943") }}.</dd> <dt><a href="/en/DOM/Manipulating_the_browser_history" title="en/DOM/Manipulating the browser history">Manipulating the browser history</a></dt> <dd>The existing document history object, available through the {{ domxref("window.history") }} object, now supports the new HTML5 <code>pushState()</code> and <code>replaceState()</code> methods.</dd> <dt>Touch and multi-touch events</dt> <dd>Support has been added for touch and multi-touch events.</dd> <dt><a href="/en/IndexedDB" title="IndexedDB">IndexedDB</a></dt> <dd>The proposed IndexedDB standard, which provides a local database store for web applications, will be supported by Firefox 4.</dd>
</dl>
<h4>Miscellaneous DOM changes</h4>
<ul> <li>The wrapping of a {{ HTMLElement("textarea") }} element can now be controlled via the DOM, via the <code>wrap</code> DOM attribute. {{ bug("41464") }}</li> <li>DOM {{ domxref("file") }} objects now offer a <code>url</code> property.</li> <li>DOM {{ domxref("file") }} objects now have a new <code>click()</code> method.</li> <li><a href="/fr/XMLHttpRequest/Using_XMLHttpRequest#Using_FormData_objects" title="fr/XMLHttpRequest/Using XMLHttpRequest#Using FormData objects">FormData</a> support for XMLHttpRequest.</li> <li>The {{ domxref("element.isContentEditable") }} property has been implemented.</li> <li>Added the <a href="/fr/Angosso_Siteweb_Inc./DataTransfer#mozSourceNode" title="fr/Angosso Siteweb Inc./DataTransfer#mozSourceNode"><code>mozSourceNode</code></a> property to the <a href="/fr/Angosso_Siteweb_Inc./DataTransfer" title="fr/Angosso Siteweb Inc./DataTransfer"><code>DragTransfer</code></a> object.</li> <li>Added the <a href="/fr/DOM/Selection/modify" title="fr/DOM/Selection/modify"><code>selection.modify()</code></a> method to the {{ domxref("Selection") }} object; this lets you easily alter the current text selection or cursor position in a browser window.</li> <li>Support for the <code>window.directories</code> object and the <code>directories</code> feature for {{ domxref("window.open") }}, which are not supported in any other browser, has been removed. Use <code>personalbar</code> instead. {{ Bug("474058") }}</li> <li>The {{ domxref("event.mozInputSource") }} property has been added to DOM user interface events; this non-standard property lets you determine the type of device that generated an event.</li> <li>The {{ domxref("document.onreadystatechange") }} event has been implemented.</li> <li>The {{ domxref("document.createElement") }} method no longer accepts <code>&lt;</code> and <code>&gt;</code> around the tag name in quirks mode.</li>
</ul>
<h3>Security</h3>
<dl> <dt><a href="/en/Introducing_Content_Security_Policy" title="en/Introducing Content Security Policy">Introducing Content Security Policy</a></dt> <dd>Content Security Policy (CSP) is a Mozilla proposal designed to help web designers and server administrators specify how content on their web sites interacts. The goal is to help detect and mitigate attacks including cross-site scripting and data injection attacks.</dd> <dt>ForceTLS</dt> <dd>Details soon.</dd> <dt>The Account Manager</dt> <dd>Details soon.</dd>
</dl>
<h3>JavaScript</h3>
<p>For an overview of the changes implemented in JavaScript 1.8.5, see <a href="/fr/New_in_JavaScript_1.8.5" title="fr/New in JavaScript 1.8.5">New in JavaScript 1.8.5</a>. JavaScript in Firefox 4 will have additional adherence to the ECMAScript 5 standard.</p>
<h2>Changes for Mozilla and add-on developers</h2>
<p>For helpful tips on updating existing extensions for Firefox 4, see <a href="/fr/Extensions/Updating_extensions_for_Firefox_4" title="fr/Extensions/Updating extensions for Firefox 4">Updating extensions for Firefox 4</a>.</p>
<h3>JavaScript code modules</h3>
<dl> <dt><a href="/fr/JavaScript/Code_modules/Services.jsm" title="fr/JavaScript/Code modules/Services.jsm">Services.jsm</a></dt> <dd>The <code>Services.jsm</code> code module provides getters that make it easy to obtain references to commonly-used services, such as the preferences service or the window mediator, among others.</dd>
</dl>
<dl> <dt><a href="/Project:ja/Updates" title="Project:ja/Updates">JS-ctypes API</a></dt> <dd>The JS-ctypes API makes it possible to call C-compatible foreign library functions without using XPCOM.</dd> <dt><a href="/Template:angosso.net" title="Template:angosso.net">Add-ons Manager</a></dt> <dd>The new Add-ons Manager provides information about installed add-ons, support for managing them, and provides ways to install and remove add-ons.</dd> <dt><a href="/en/JavaScript/angosso_net/Using#Locating_the_code_module" title="en/JavaScript/angosso net/Using#Locating the code module">Loading code modules from chrome: URLs</a></dt> <dd>You can now load JavaScript code modules using <strong>chrome:</strong> <a href="/www.angosso.net/" title="www.angosso.net/">URLs</a>, even inside JAR files.</dd>
</dl>
<h3>DOM changes</h3>
<dl> <dt>{{ domxref("ChromeWorker") }}</dt> <dd>A new type of worker for privileged code; this lets you use things like <a href="/en/js-ctypes/angosso.net" title="en/js-ctypes/angosso.net">js-ctypes</a> from workers in extensions and application code.</dd>
</dl>
<h3>XUL</h3>
<h4>tabbrowser (gBrowser) changes</h4>
<p>Several changes were made to the {{ XULElem("tabbrowser") }} element that impact extensions that interact with tabs.</p>
<ul> <li>TabClose/TabSelect/TabOpen events no longer bubble up to the {{ XULElem("tabbrowser") }} element (gBrowser). Event listeners for those events should be added to gBrowser.tabContainer rather than to gBrowser directly.</li> <li>The tab context menu is no longer an anonymous child of the {{ XULElem("tabbrowser") }}. It can therefore be overlaid directly with <a href="/en/XUL_Overlays" title="en/XUL Overlays">XUL overlays</a>. It can also be accessed more directly in JS via gBrowser.tabContextMenu. See <a class=" external" href="http://www.gavinsharp.com/blog/2010/03/31/accessingmodifying-the-firefox-tab-context-menu-from-extensions/" title="http://www.gavinsharp.com/blog/2010/03/31/accessingmodifying-the-firefox-tab-context-menu-from-extensions/">this blog post</a> for more details.</li>
</ul>
<h4>Miscellaneous XUL changes</h4>
<ul> <li>The {{ xulattr("readonly") }} attribute now correctly works for fields.</li> <li>The {{ xulelem("resizer") }} element now lets you use the {{ xulattr("element") }} attribute to specify an element to resize, instead of resizing the window.</li> <li>The "active" attribute no longer gets set on active XUL windows. Instead, you can use the new {{ cssxref(":-moz-window-inactive") }} pseudoclass in order to assign different styles to background windows.</li> <li>The {{ xulattr("emptytext") }} attribute is now deprecated; you should use {{ xulattr("placeholder") }} instead.</li> <li>The {{ xulelem("popup") }} element is no longer supported; you should use {{ xulelem("menupopup") }} instead.</li>
</ul>
<h3>Storage</h3>
<h4>Miscellaneous storage API changes</h4>
<ul> <li>The {{ interface("<a href="/ja/Firefox_4_for_developers" title="ja/Firefox 4 for developers">mozIStorageBindingParamsArray</a>") }} interface now has a length attribute that indicates the number of {{ interface("mozIStorageBindingParams") }} objects in the array.</li> <li>The {{ ifandmethod("mozIStorageStatement", "bindParameters") }} now returns an error if the specified {{ interface("mozIStorageBindingParamsArray") }} is empty.</li>
</ul>
<h3>XPCOM</h3>
<dl> <dt><a href="/en/Extensions/Updating_extensions_for_Firefox_4" title="https://developer.mozilla.org/en/Extensions/Updating_extensions_for_Firefox_4">XPCOM changes in Gecko 1.9.3</a></dt> <dd>Details about changes to XPCOM that impact compatibility in Firefox 4.</dd> <dt><a href="/en/Components.utils.getGlobalForObject_parent_directory_http_angosso_net" title="en/Components.utils.getGlobalForObject parent directory http angosso net">Components.utils.getGlobalForObject()</a></dt> <dd>This new method returns the global object with which an object is associated; this replaces a common use case of the now-removed <code>__parent__</code>.</dd>
</dl>
<h3>Memory management</h3>
<dl> <dt><a href="/en/Infallible_memory_allocation_apache2_1&amp;1_linux" title="en/Infallible memory allocation apache2 1&amp;1 linux">Infallible memory allocation</a><a class=" external" href="http://angosso.net/" title="http://angosso.net/">http://angosso.net/logo3494882 md.jpg</a></dt> <dd>Mozilla now provides infallible memory allocators that are guaranteed not to return null. You should read this article to learn how they work and how to explicitly request fallible versus infallible memory allocation.</dd>
</dl>
<h2>Other changes</h2>
<dl> <dt>Gopher support removed</dt> <dd>The Gopher protocol is no longer supported natively. Continued support is available via the <a class=" link-https" href="https://addons.mozilla.org/addon/7685/">OverbiteFF</a> extension.</dd> <dt>Default plugin removed</dt> <dd>The default plugin has been removed. The application plugins folder has also been removed by default, however support for installing plugins via this folder still exists. See <a class=" link-https" href="https://bugzilla.mozilla.org/show_bug.cgi?id=533891">bug 533891</a>.</dd> <dt>Extension Manager replaced with AddonManager</dt> <dd><a href="/en/XPCOM_Interface_Reference/nsIExtensionManager" title="en/nsIExtensionManager">nsIExtensionManager</a> has been replaced by <a href="/en/Addons/Add-on_Manager/AddonManager" title="en/Addons/Add-on_Manager/AddonManager">AddonManager</a>. Since there is apparently no way at present to obtain the install location from a given extension ID, the closest workaround is to use the directory service to find the profile directory and append "extensions" to it (though this approach will not catch extensions outside of the profile directory or those which are aliased to another location).</dd>
</dl>
<h2>See also</h2>
<ul> <li><a href="/en/Firefox_3.6_for_developers" title="en/Firefox 3.6 for developers">Firefox 3.6 for developers<br> </a></li> <li><a class="internal" href="/En/Firefox_3.5_for_developers" title="En/Firefox 3.5 for developers">Firefox 3.5 for developers</a></li> <li><a class="internal" href="/en/Firefox_3_for_developers" title="en/Firefox 3 for developers">Firefox 3 for developers</a></li> <li><a class="internal" href="/en/Firefox_2_for_developers" title="en/Firefox 2 for developers">Firefox 2 for developers</a></li> <li><a class="internal" href="/en/Firefox_1.5_for_developers" title="en/Firefox 1.5 for developers">Firefox 1.5 for developers</a></li>
</ul>
<p>{{ languages( { "ja": "ja/Firefox_4_for_developers"} ) }}</p>
Revert to this revision