Is there any way to fix the error that a JavaScript & causes in w3 validation? The problem is that i have to use && in a if statement and these two &&'s causes errors in w3 validation.
EDIT: Same problem with "<" and ">".
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2Would be better if you shown some code.LiraNuna– LiraNuna2009-09-27 10:35:48 +00:00Commented Sep 27, 2009 at 10:35
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What HTML version do you use?Gumbo– Gumbo2009-09-27 10:35:54 +00:00Commented Sep 27, 2009 at 10:35
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By the way: A logical AND can always represented by a logical OR and NOT: A && B = !(!A || !B)Gumbo– Gumbo2009-09-27 10:58:33 +00:00Commented Sep 27, 2009 at 10:58
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4 Answers
There are a few things you can do.
You can enclose it within HTML comments:
<script type="text/javascript">
<!--
if (foo && bar) ...
//-->
</script>
You can enclose it in a CDATA section:
<script type="text/javascript">
// <![CDATA[
if (foo && bar) ...
// ]]>
</script>
You can include in in a file instead:
<script src="foobar.js" type="text/javascript"></script>
3 Comments
T.J. Crowder
+1 to using a JavaScript file. The other two options are a bit dated, use a modern DOCTYPE instead.
Eli Grey
Make sure to comment out the HTML comment start. If E4X is enabled (
type contains ;e4x=1), the code inside would be a comment literal.
Talvi Watia
@TJ I've found some .js will crash if its not inline.. (i.e. googlemap v3)
The primary answer is: Use JavaScript files for JavaScript, not HTML files, and use the src attribute of script tags. (Combine all your JS into one file, minimize, gzip, etc. for performance.)
But, you can embed JavaScript in HTML if absolutely necessary. Use a valid, modern DOCTYPE and you don't have to resort to comment tags and CDATA sections.
Valid HTML5 example:
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-type" content="text/html;charset=UTF-8">
<title>Example</title>
<script type='text/javascript'>
function foo() {
var a = 1, b = 2;
if (a && b) {
alert("Both");
}
if (a < b) {
alert("a < b");
}
if (a > b) {
alert("a > b");
}
}
</script>
</head>
<body>
<p>Hi there</p>
</body>
</html>
That will also validate as HTML4 strict if you change the doctype to
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
Note that in both cases, you need to be careful about end tags in your script --
This causes the problem:
<script type='text/javascript'>
alert("</td>");
</script>
This solves the problem by prefacing the slash with a backslash (or you can break the end tag up into separate string literals):
<script type='text/javascript'>
alert("<\/td>");
// -or-
alert("<" + "/td>");
</script>
But again, the basic answer is: Don't embed JavaScript within HTML files when you can avoid it, use JavaScript files for that.
Comments
Based on your description, I suspect that you're talking about script that's inside an event property in an HTML tag (such as onclick). In that event, the script code needs to be HTML encoded. Elijah hit the nail on the head there.
For example:
<input type="submit" onclick="if(somevar && othervar) callFunc("clicked");">
You do not need to do that inside a <script></script> block.
1 Comment
Joanne C
hmm... Pushed down, not sure why. Whomever did that may want to read the standard, it most definitely applies to both HTML and XHTML. The same applies for URLs in anchor tags, etc. as well.
Escape & with &, < with <, and > with >.
5 Comments
Quentin
This works great in XHTML … but not HTML-compatible XHTML where it will just break.
Quentin
I don't need to test this trivial thing. It's a very basic part of the differences between HTML and XHTML. That said, here is a test case: dorward.me.uk/tmp/no-it-doesnt-work.html (it errors, as expected, in Firefox. I can't be bothered to test in other browsers).
Joanne C
Your test case is inside the script tags where it does not need to be HTML encoded. However, inside the HTML (on a tag property), it most definitely does need to be encoded as with the example I gave above.
Quentin
If you mean "attribute value", then that is different. The question didn't specify if it was about attribute values or script elements. Script elements are more likely, as intrinsic event attributes tend to have simple function calls in them, so assuming they were what was being discussed was a reasonable assumption.
Joanne C
Based on the original posting, I actually assumed it was on an attribute and not inside a script block. I'm not sure if Elijah made the same assumption, though he didn't say as much.