检查样式表文件中后面代码中的css类是否存在

Question

I control styles for a set of pages in a common utility method. What i would like to do is check the .css file to see if a css class exists; if it does then pick it, else pick the default.

say PageA.aspx and PageB.aspx both use styles.css that contains .default{...} if i wanted PageA.aspx to be styled differently, i would just add another entry in styles.css .PageA{....} etc. At runtime, it will search for a css class named PageB, since it does not find it, it will default to the default class.

Question is how do i check the .css file to find out if a particular css class exists in the code-behind.

Thanks

Answer 1

The simple way would be to apply the default style, and then the pageA style. The browser should ignore the pageA declaration if it doesn't exist.
However I think the Right Thing™ would be to handle this in ASP or use separate files as Seb suggests.

Answer 2

Many questions in SO ask for a particular solution but don't state the real problem behind, so it's difficult to answer properly.

But I suspect what you're asking could be achieved far easier by splitting styles in 3 different files and including just what you need:

• styles.css: common styles for PageA and PageB
• styleA.css: rules applying only for PageA
• styleB.css: rules applying only for PabeB, but with the same name used in styleA.css

Then, you include styleA.css or styleB.css depending on which page you're showing and that's it.

If this doesn't answer your question, then you might post what's your real problem instead of the solution you're trying to code - which might not be the best solution.

BTW: I don't think there's a way to know which CSS classes are defined; you just set and unset them.

Answer 3

您可以使用StreamReader加载css文件（因为它是一个文本文件），然后使用String.IndexOf()方法逐行搜索它，但这并不是每次页面加载都非常有效。

Answer 4

您的问题没有多大意义，但是由于CSS不是一种编程语言，因此，如果您想知道另一个文件中的内容，则必须在其他地方进行操作。