CSS 中可以运算吗？？比如 width:100%-10px;

lxy_lxy 2008-11-06 09:35:05

CSS 中可以运算吗？？比如如下：

.div1
{
width:100%-10px;
height:50px;
color:#ffffff;
}

...全文

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F91KDASH 2010-08-12

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.div1
{
width:expression((obj.width - 10) + "px");
height:50px;
color:#ffffff;
}

原來還可以這麼用，學習了。

csxrzeng 2009-02-18

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还是不能啊~~~

ShowWin 2008-11-09

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css 可以使用表达示。。但是不推荐。占资源太严重了。。

gengwanshanreally 2008-11-08

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不报错就正确，呵呵！

greatverve 2008-11-08

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width:expression((obj.width - 10) + "px");
学到一点，一会试试。

lxy_lxy 2008-11-08

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[Quote=引用 3 楼 yoursWTR 的回复:]
可以在CSS里面用JS

.div1
{
width:expression((obj.width - 10) + "px");
height:50px;
color:#ffffff;
}
[/Quote]
这样也可以呀···可是 obj 指的是什么呢···？？哪一个对象呢~~？

Silver_1987 2008-11-07

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应该只能用JS来控制CSS里的东西吧

wfyfngu 2008-11-07

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IE8开始不支持CSS中使用表达式。



What is a CSS expression ?



Also known as ‘Dynamic Properties’, this proprietary CSS extension was introduced in Internet Explorer 5. Long before JavaScript libraries such as jQuery or Dojo were conceived, it allowed web developers to dynamically bind script to the page through CSS selectors. As an example, the following CSS declaration updates the background color of certain page blocks depending on the time of day :



div.title { background-color: expression( (new Date()).getHours()%2 ? "#B8D4FF" : "#F08A00" ); }



Why end support for expressions ? 



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 

Because they expose a script execution context, CSS expressions constitute a possible script injection attack vector. 

Are expressions still available in IE7 and Quirks mode ?



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.



Pages on my web site depend on CSS expressions.  How does this affect me ?



Thanks to IE8’s new layout engine, most expressions written to work around CSS 2.1 bugs and shortcomings should no longer be needed; we expect unsupported or incorrectly interpreted properties to work in a standard, interoperable way. For those expressions supporting more specific purposes, anything they do is inherently achievable using standard JavaScript, usually interoperably and at lower runtime costs. The specifics will of course depend on your application. Based on your feedback to this post, we may visit examples in future installments.



Ending support for expressions - a feature often used to fix the very issues we have worked hard to address in this release – helps make IE8 more standard, faster and more secure for our users. 



Sylvain Galineau 

Program Manager



Posted by ieblog | 78 Comments 

Filed under: Developers, Security