14 DAY TRIAL // Internet Explorer 9 has been optimized so it won’t break the web, just as other Internet Explorer releases before it, including IE8. The level of optimization poured into IE9 in terms of backward compatibility involves building the browser so that it will seamlessly render different markup, especially markup that wasn’t tailored to the next generation of IE, without users noticing any difference in the way they experience favorite websites, even though the browser version has changed. As far as Internet Explorer 9 is concerned, this is done through ensuring that the browser sports a number of different modes.
Specifically, Microsoft needs IE9 to play nice with websites and content designed specifically for the latest IE version, but also with that tailored to older releases, including IE6, IE7 and IE8. It all comes down to browser web standard support. In this context, IE9 has embraced modern web standards such as HTML5 and CSS3. Websites created by leveraging the entire span of standards supported by IE9 will render incorrectly in IE7 or IE8, for example. However, not the same is valid vice versa.
“IE9 supports the four modes: IE9’s Standards mode (the most standards-compliant mode), Quirks mode, IE7 Standards mode and IE8 Standards mode,” revealed Marc Silbey, IE Program Manager. “First, there is IE9’s Standards mode. It is IE9’s most standards-compliant, interoperable and fastest mode. It includes support for SVG, CSS3, DOM Level 3, and many other standards-based features. This is IE9’s default mode. We want site developers to use this mode as part of getting us all to the goal of running ‘same markup’.”
The first Developer Preview of Internet Explorer 9 is currently available for download, and users can visit the IE9 Test Drive site, in order to test drive the browser. But while it brings a consistent evolution to the table in terms of web standards support, IE9 will also render IE6-specific websites flawlessly.
“Many real world sites still rely on legacy modes. IE9 supports Quirks mode for sites such as atlaspost.com, chase.com, and zapak.com. The lack of doctype on these sites indicates that they want to render in Quirks mode. (…) Markup that relies on Quirks mode behavior doesn’t always render as intended in other modes,” Silbey added.
What Microsoft aims to deliver with IE9 is a “just works” browser. Users currently running an older version of IE, or any other browser for that matter, should be able to install IE9 and not notice any differences on the websites they visit. In addition to the IE9 and Quirks modes, IE9 also features the IE7 Standards mode and IE8 Standards mode.
“Without these modes in IE9, site developers would have to go back and re-work sites that relied on specific behaviors,” Silbey said. “Ultimately we want the same markup to work across all browsers. In the meantime, we want the markup you wrote for IE7 and IE8 to continue to work in IE9. Site developers can add the X-UA-Compatible meta tag or HTTP header to give themselves time to update their sites to use the same markup across browsers.”
Internet Explorer 9 (IE9) Platform Preview is available for download here.