Common errors in xhtml

**orlando** · 11-05-2008 09:56 AM

hi
I m here again for sharing my little ideas with you. hope you like it and give the good responce. plz post ur views.

here is some common errors occur in XHTML.

Failing to realize that documents won’t be treated as XHTML unless they are served with an appropriate XML MIME type
Not closing empty elements (elements without closing tags in HTML4)
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<br>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<br />[/SIZE][/FONT]
  Note that any of these are acceptable in XHTML: [FONT=Courier New, monospace][SIZE=2]<br></br>[/SIZE][/FONT], [FONT=Courier New, monospace][SIZE=2]<br/>[/SIZE][/FONT] and [FONT=Courier New, monospace][SIZE=2]<br />[/SIZE][/FONT]. Older HTML-only browsers interpreting it as HTML will generally accept [FONT=Courier New, monospace][SIZE=2]<br>[/SIZE][/FONT] and [FONT=Courier New, monospace][SIZE=2]<br />[/SIZE][/FONT].
Not closing non-empty elements
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<p>This is a paragraph.<p>This is another paragraph.[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<p>This is a paragraph.</p><p>This is another paragraph.</p>[/SIZE][/FONT]
Improperly nesting elements (Note that this would also be invalid in HTML)
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<em><strong>This is some text.</em></strong>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<em><strong>This is some text.</strong></em>[/SIZE][/FONT]
Not putting quotation marks around attribute values
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<td rowspan=3>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<td rowspan="3">[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<td rowspan='3'>[/SIZE][/FONT]
Using the ampersand character outside of entities
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<title>Cars & Trucks</title>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<title>Cars & Trucks</title>[/SIZE][/FONT]
Using the ampersand outside of entities in URLs (Note that this would also be invalid in HTML)
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<a href="index.php?page=news&style=5">News</a>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<a href="index.php?page=news&style=5">News</a>[/SIZE][/FONT]
Failing to recognize that XHTML elements and attributes are case sensitive
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<BODY><P ID="ONE">The Best Page Ever</P></BODY>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<body><p id="ONE">The Best Page Ever</p></body>[/SIZE][/FONT]
Using attribute minimization
- Incorrect: [FONT=Courier New, monospace][SIZE=2]<textarea readonly>READ-ONLY</textarea>[/SIZE][/FONT]
- Correct: [FONT=Courier New, monospace][SIZE=2]<textarea readonly="readonly">READ-ONLY</textarea>[/SIZE][/FONT]
Mis-using CDATA, script-comments and xml-comments when embedding scripts and stylesheets.
- This problem can be avoided altogether by putting all script and stylesheet information into separate files and referring to them as follows in the XHTML [FONT=Courier New, monospace][SIZE=2]head[/SIZE][/FONT] element.

[FONT=Courier New, monospace][SIZE=2]<link rel="stylesheet" href="/style/screen.css" type="text/css" />[/SIZE][/FONT]
[FONT=Courier New, monospace][SIZE=2]<script type="text/javascript" src="/script/site.js"></script>[/SIZE][/FONT]
Note: The format [FONT=Courier New, monospace][SIZE=2]<script …></script>[/SIZE][/FONT], rather than the more concise [FONT=Courier New, monospace][SIZE=2]<script … />[/SIZE][/FONT], is required for HTML compatibility when served as MIME type [FONT=Courier New, monospace][SIZE=2]text/html[/SIZE][/FONT].

- If an author chooses to include script or style data inline within an XHTML document, different approaches are recommended depending whether the author intends to serve the page as [FONT=Courier New, monospace][SIZE=2]application/xhtml+xml[/SIZE][/FONT] and target only fully conformant browsers, or serve the page as [FONT=Courier New, monospace][SIZE=2]text/html[/SIZE][/FONT] and try to obtain usability in Internet Explorer 6 and other non-conformant browsers.