How to correctly use JavaScript and CSS in XHTML documents_HTML/Xhtml_Webpage Production

In more and more websites, the use of XHTML is replacing HTML4 at a very fast speed. However, some mainstream browsers currently do not support XHTML very well. In addition, some web page producers are not sure about the differences between XHTML and HTML4. Insufficient understanding of the differences makes XHTML's progress in WEB development slow.


XHTML is XML not HTML

Currently, one of the major misunderstandings about XHTML is that it is another version of HTML. This misunderstanding is caused by the fact that Microsoft Internet Explorer only supports XHTML in the MIME format text/html rather than the recommended application/xhtml xml format.

When an XHTML page is parsed in the MIME format of text/html, it is no different from an HTML page, and when it is parsed in the MIME format of text/xml or application/xhtml xml, it will comply with Strict XML writing and display rules.

The correct XHTML format is an XML program and needs to follow the following strict rules when writing:

1. Characters )

2. The content of the comment tag () cannot contain two consecutive dashes (--)

3. Contained in the comment Content within tags () will be ignored


Problems in style and script content

Content within style and script tags There will be some differences when XHTML is parsed in XML format (rather than HTML format).

JavaScript contains characters that cannot exist in XHTML

Some special characters in Javascript are characters that cannot exist outside the CDATA tag of XHTML.



NOTE: The example code above is not well-formed XHTML because it uses the tag " which is not allowed in XHTML or XML "

Use comments in style and script content


Authors who are familiar with HTML usually know that putting the content of style and script tags inside comment tags will Hide these in browsers, but some browsers don't understand them.
)



style and javascript contain two consecutive dashes (--)


Another problem that arises when using comment tags in JavaScript on XHTML pages is that JavaScript will In the case of two consecutive dashes (--):




Use CDATA instead of comment

will Putting the content in the script tag into a CDATA block can well handle the problem of two consecutive horizontal bars in comments, but this will make some lower version browsers not support it because they cannot understand XML. Fortunately, we can achieve compatibility by commenting the CDATA block using comment characters in JavaScript.



Recommended xhtml and html compatible processing method Do not write style and script directly in the XHTML page, a A good alternative is to use external files to write CSS and JavaScript and then import them in XHTML. This recommended solution looks very good. Anyway, it will make the process of converting the page from text/html to application/xhtml xml, at least in the next few years, without any problems.