Internet Explorer Preview 3 comes with new HTML5 improvements, most notably being: audio, video and canvas, a faster JavaScript engine, more DOM and CSS features supported, support for embedded fonts, closing the HTML5 implementation gap with other browsers, and performing better in some areas due to hardware acceleration.
IE 9 Preview 1 and 2 included hardware acceleration for text, images and vector graphics, while IE 9 Preview 3 adds video, audio and canvas rendered on GPU rather than CPU. Microsoft has decided to run all the web page content through the underlying Windows on computer’s graphics card for better performance, making IE “the first browser that uses hardware acceleration for everything on the web page, on by default, available today for developers to start using for their modern site development.”
Canvas. One of the most desired features was Canvas. IE9 Preview 3 supports it as the following demos show that: Asteroid Belt, Fish Tank, and Amazon Shelf.
Audio & Video. IE 9 also adds support for HTML5 <audio> and <video> elements supported via the H.264 codec. The Video Panorama site contains a number of videos developers can use to test IE 9’s ability to render video natively.
JavaScript. The Chakra JavaScript engine supports the ECMA-262 standard and even adds support for some of the new features in ECMA-262 Fifth Edition (PDF), aka ES5:
This support for ES5 includes new array and object methods, as well as other language enhancements for working with strings and dates. The test drive site includes samples where you can try new array methods and play a game built with new ES5 capabilities. You can learn more about how we used ES5 arrays with a video look “under the hood” for the Tile Switch game.
Microsoft’s latest Webkit Sunspider test results show that IE 9 has cached up on pure JavaScript processing speed, being close to Opera 10.6 and Chrome 6.0 beta:
DOM, CSS. IE 9 Preview 3 adds support for the following DOM&CSS features: DOM Traversal, full DOM L2 and L3 events, getComputedStyle from DOM Style, CSS3 Values and Units, and CSS3 multiple backgrounds. Also, IE9 now supports embedded fonts using the Web Open Font Format (WOFF) based on CSS3 font face done through DirectWrite rendering with sub-pixel precision for a quality rendering of text.
Based on IE 9 Preview 3, Microsoft has updated the Testing Center with new tests and test results. Microsoft reported they have submitted the tests to W3C but there is still not a common pool of compliance tests that all browser vendors agree upon. That would be a step forward in making sure that all browsers are truly HTML5 compliant and do not introduce differences among them affecting web development. On Acid3 IE 9 Preview 3 scores 83 compared to 68 for Preview 2.