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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 ">".

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 ">".

  • javascript
  • w3c-validation
Share Improve this question asked Sep 27, 2009 at 10:31 PokuPoku 3,17810 gold badges48 silver badges65 bronze badges 3
  • 2 Would be better if you shown some code. – LiraNuna Commented Sep 27, 2009 at 10:35
  • What HTML version do you use? – Gumbo Commented Sep 27, 2009 at 10:35
  • By the way: A logical AND can always represented by a logical OR and NOT: A && B = !(!A || !B) – Gumbo Commented Sep 27, 2009 at 10:58
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4 Answers 4

Reset to default 18

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>

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.

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 &amp;&amp; othervar) callFunc(&quot;clicked&quot;);">

You do not need to do that inside a <script></script> block.

Escape & with &amp;, < with &lt;, and > with &gt;.

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