IE9 Platform Preview 4 Available Now

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IE9 Platform Preview 4 is available now at the IE9 test drive site. What's new in preview 4?

  • JavaScript is now natively integrated inside the browser (not bolted on the side)
  • Single shared DOM between IE and JavaScript engine
  • Improved performance improvements across the product
  • Increased support for standards and an improved Acid 3 score as a result
  • Additional tests submitted to the working groups at the W3C
  • Continue to address feedback from Connect

There's also a boatload of new demos on the testdrive site.

This is the last platform preview before the IE9 Beta and it's a good idea to start planning now for readying your sites for IE9:

  • Test your site in IE9 Standards Mode
  • Send IE9 the same standards-based markup your site sends other browsers
  • Use feature detection, not browser detection to handle any cross browser differences in behavior or feature support
  • Report issues on Connect if your site doesn’t look or work right, and you’re giving it the same code as you’re giving to other modern browsers
  • Consider the experience for IE9 Beta users if you find that sending the same markup creates more issues than you can resolve in your production site
  • Take advantage of HTML5, CSS3, SVG, DOM, ES5, and more…

Lots more detail on this (and IE9 Preview 4 generally) on the IE Team Blog.

Note: There's no need to uninstall earlier preview builds, Preview 4 will install over the top quite happily.