With some hesitancy or may be confusion I have learned that the CSS expressions are no longer supported in IE8 standards mode, I mean when I read in ajaxian this post:
The CSS expressions of old will no longer work in IE 8. Whenever a feature goes away in IE, Ajax hackers get worried, as many hacks rely on quirks or proprietary features of the browser.
In the IEBlog here is what was exactly said:
Why end support for expressions?Now it is real that for CSS 2.1 users the time will be convenient to finally have a full support browser of their version without checking/validating every time their CSS code under IE6. But the question is what the negative impact we really have?
- To comply with standards
- Expressions are proprietary to Internet Explorer and as such not interoperable.
- A common use-case for expressions was to fix IE bugs or to emulate those CSS 2.1 features not yet supported by the browser, for example, min-width and max-width. We have not only worked hard to fix these bugs in IE8 but our new layout engine supports the missing features natively.
- To improve performance
- Expressions evaluation has a high runtime cost; web performance experts like Steve Souders recommend avoiding them to improve front-end performance
- To reduce the browser attack surface
Are expressions still available in IE7 and Quirks mode ?
- Because they expose a script execution context, CSS expressions constitute a possible script injection attack vector.
- Yes. For backward compatibility, CSS expressions are still executed in Quirks and IE7 Strict modes. But starting with IE8 Beta 2, they are ignored in IE8 Standards mode.
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