TOOLS - CSS: Professional Techniques for Modern Layout - page 36

h e script itself will make sure it's only run when needed, so you could skip the conditional
comments. Doing that, though, means that every visitor ends up downloading it whether the
browsers will ever run it or not. With the conditional comments, you make sure that only
those browsers that have any chance of running the script will bother loading it.
As noted, there are also earlier versions of the script meant to bring previous versions of IE up
to the level of IE7 or IE8. If you i nd that IE9.js doesn't suit your needs, try one of the earlier
versions.
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