What's New in Internet Explorer 8

What's New in Internet Explorer 8

Note: This documentation is about the platform features of Internet Explorer 8 Beta 1.
Accessibility
In response to the increase in user interface (UI) complexity on the Web, the Web Accessibility Initiative group has defined a roadmap for Accessible Rich Internet Applications (ARIA), which introduces ways for Web site authors to define how custom UI elements are accessed. ARIA accomplishes this by defining a set of HTML attributes that map back to common UI controls. As a result, users with disabilities can access Web sites with a rich interaction model. By exposing ARIA through the Microsoft Active Accessibility API in Internet Explorer 8, assistive technologies that already use Active Accessibility can also support ARIA easily.
The alt attribute is no longer displayed as the image tooltip when the browser is running in IE8 mode. Instead, the target of the longDesc attribute is used as the tooltip if present; otherwise, the title is displayed. The alt attribute is still used as the Active Accessibility name, and the title attribute is used as the fallback name only if alt is not present.
For more information, see What's New for Accessibility in Internet Explorer 8.

ActiveX Improvements
Internet Explorer 8 offers greater control over who can install Microsoft ActiveX controls and on which sites they are allowed to run.

Per-site ActiveX
Nearly half of all ActiveX controls meant to run on only one site do not use any form of site-locking technology. This means that many controls are not secure by default and could be misused by malicious Web sites. To prevent this in Internet Explorer 8, users can decide whether to allow ActiveX controls to run on a site-by-site basis.
Non-administrator installation
Standard users (those without administrator privileges) can install ActiveX controls to their user profiles without a UAC prompt or administrator involvment of any kind. In the event that a user does install a malicious ActiveX control, only the user profile is affected; however, the system itself is not compromised.
Activities and WebSlices
Because the Internet has become increasingly interactive, Internet Explorer 8 makes it easier to interact with and subscribe to content on a Web page.
Activities are a form of browser extension that acts on user-selected content by sending the information to a service of the user's choosing. Services can perform actions on the content (such as "email" or "bookmark") or provide more information ("translate" or "map"). Users can install and access their own activities from the browser context menu, making their browsing experience more efficient.
For more information, see Activities in Internet Explorer 8.
WebSlice enables users to subscribe to specially marked content on a Web page. When the content changes, the user receives a notification on the Favorites Bar. A WebSlice can be previewed without an additional navigation.
See also, Subscribing to Content with WebSlice.

AJAX Enhancements
Asynchronous JavaScript and XML (AJAX) is changing the way Web applications are built. Internet Explorer 8 brings new functionality to the XMLHttpRequest object that enables AJAX applications.

AJAX Navigation — Client requests that do not trigger traditional page navigation can now update the hash property, which allows the Back button to function appropriately.
Connection Events — Where reliability is of top concern, AJAX applications can exit gracefully if the call is canceled or times out.
Cross-domain Request (XDR) — To address the limitations of existing mashup development, Internet Explorer 8 introduces the XDomainRequest object to allow restricted and secure communication between untrusted modules in the page. The browser shields the user from potential threats while allowing powerful cross-site interaction.
Cross-document messaging — Documents in different domains can securely exchange data using postMessage.
More Connections — Internet Explorer 8 raises the number of connections per host by default, for a potential drop in page load times and increased parallelism in AJAX scenarios.
For more information, see:
XMLHttpRequest Enhancements in Internet Explorer 8
Connectivity Enhancements in Internet Explorer 8

CSS Compliance
Internet Explorer 8 is the most CSS-compliant release yet. Here are some highlights.
Data URI — This mechanism allows a Web page author to embed small entities directly within a Uniform Resource Identifier (URI), rather than using the URI to identify a location from which to retrieve the entity. This is primarily of interest for small images (such as a bullet) used within CSS or layout.
New Pseudo-classes — The following are new to Internet Explorer 8:
:before and :after— In conjunction with the new content rule, authors can describe dynamic content to appear before and after elements in the document tree.
:focus— This pseudo-class applies while an element has input focus.
outline — Enables elements to be highlighted without affecting their size. The outline is a shorthand property for outline-color, outline-style, and outline-width.
Printing — The following properties have been added:
page-break-inside
widows
orphans

Table Layouts — For many years, tables were the preferred layout mechanism on the Internet. With Internet Explorer 8, it is now possible to apply table-style formatting to non-table elements using the display attribute. In practice, CSS tables are more permissive than HTML markup; tables created with CSS rules will nest elements to become valid, whereas tables created with HTML will close containers to avoid unexpected nesting.
For the complete list, see CSS Improvements in Internet Explorer 8.

Developer Tools

Internet Explorer 8 enhanced Developer Tools expose the internal representation of Web pages to help research and resolve problems involving HTML, Cascading Style Sheets (CSS), and script.
CSS Tool — Display various rules defined by style sheets loaded by your Web page.
Script Debugging — The built-in lightweight debugger lets you set breakpoints and step through client-side script without leaving Internet Explorer.
Version Mode Switching — Switch into different browser modes to test content for standards compliance.
For more information, see:
Discovering the Internet Explorer 8 Developer Tools
Developer Tools: Script Debugging Overview
Document Compatibility Mode
Internet Explorer 8 has made deliberate investments in a new layout engine with full CSS 2.1, strong HTML 5 support, and interoperability fixes for the Document Object Model (DOM). The highest level of standards support is on by default for sites that specify a strict !DOCTYPE. Website authors can select IE7 mode rendering in Internet Explorer 8 with the following meta tag: meta equiv="X-UA-Compatible" content="IE=7"
Copy Code < meta content="IE=" equiv="X-UA-Compatible" >
For more information, see Defining Document Compatibility.

DOM Storage
Storing web application data within a local cache opens up new possibilities for a future class of Web applications by storing and loading user data directly on a user's hard drive. The future of AJAX will extend its reach beyond client/server interactions and into local data storage addressed from any Web page and interpreted by the client Web browser. A Web application can write to local storage when disconnected from the Internet and synchronize local changes when an active Internet connection returns. A scriptable online/offline connectivity event fires on connection status change and will be available to all pages.
See also, Introduction to DOM Storage.

HTML Improvements
The new HTML 4.01 implementation is now much more interoperable. These improvements include:
The object tag image fallback is interoperable with other browsers. For example, an object tag without dimensions is now the same size as the image instead of 0 x 0 pixels.
The button element submits its value attribute instead of its innerHTML, which means you can use the button element for cross-browser FORM scenarios.
The getElementById method is now case-sensitive, and it no longer incorrectly searches using the NAME attribute.
The setAttribute method is now case-insensitive; you do not need to use "camel case" (for example, "camelCaseWord") to specify attributes. It also correctly identifies HTML attributes such as CLASS and FOR.
For a complete list, see HTML Enhancements in Internet Explorer 8.
Protected Mode Cookies
Protected Mode restricts file writes to low integrity locations, including cookies. In Internet Explorer 8, medium-integrity applications can access low integrity cookies without user interaction by using IEGetProtectedModeCookie and IESetProtectedModeCookie. As always, applications that use cookies downloaded from the Internet should assume these cookies contain malicious data.

Selectors API
Use the power of CSS selectors to rapidly locate DOM elements. The API introduces two methods, selectElement and selectAllElements, that take a selector (or group of selectors) and return the matching DOM elements. With these methods, it is easier to match a set of element nodes based on specific criteria. The Selectors API provides significantly faster performance over non-native implementations.
For more information, see Selecting Objects with JavaScript.

Tab Isolation and Concurrency
In Internet Explorer 8, the browser frame is "loosely coupled" with the tabs inside it. This means that pages that use Protected Mode and those that don't may be hosted within the same instance of the browser. Additionally, glitches and hangs don't bring down the entire browser, thereby ensuring that poorly written extensions do not significantly impact the performance or reliability of Internet Explorer 8.

Source: Microsoft