HTML and CSS Reference
In-Depth Information
Escape Ampersand
Convert
&
to
&
.
<a href="/discipline/470.html">Health
&
Kinesiology</a>
<img src="text.gif" alt="Texts
&
Technology" />
<a href="/discipline/470.html">Health
&
Kinesiology</a>
<img src="text.gif" alt="Texts
&
Technology" />
Motivation
Although most browsers can handle a raw ampersand followed by whitespace, an ampersand not followed by
whitespace confuses quite a few. An unescaped ampersand can hide content from the reader. Even if you aren't
transitioning to full XHTML, this refactoring is an important fix.
Potential Trade-offs
None. This change can only improve your web pages.
However, you do need to be careful about embedded JavaScript within pages. In these cases, the ampersand
usually cannot be escaped. Sometimes you instead can use an external script where the escaping is not
necessary. Other times, you can hide the script inside comments where the parser will not worry about the
ampersands.
Mechanics
Because this is a bug that results in visible problems, there usually aren't many cases of this. You can typically
find all the occurrences and fix them by hand.
I don't know one regular expression that will find all unescaped ampersands. However, a few simple expressions
will usually sniff them all out. First, look for any ampersand followed by whitespace. This is never legal in HTML.
This regular expression will find those:
&\s
If the pages don't contain embedded JavaScript, simply search for
&(\s)
and replace it with
\&\1
. A
validator such as xmllint or HTML Validator will easily find all cases of these, along with a few cases the simple
search will mix. However, if pages do contain JavaScript, you must be more careful and should let Tidy or
TagSoup do the work.
Embedded JavaScript presents a special problem here. JavaScript does not recognize
&
as an ampersand.
JavaScript code must use the literal
&
character. I normally place the script in an external file or an XML
comment instead:
<script type="text/javascript" language="javascript">
<!--
if (location.host.toLowerCase().indexOf("example.com") < 0 &&
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