JavaScript Notes Plus
Welcome to Perishable Press! This article covers a plethora of useful JavaScript tips and tricks. For more excellent JavaScript information, check out the JavaScript tag archive. If you like what you see, I encourage you to subscribe to Perishable Press for a periodic dose of online enlightenment ;)
Nifty JavaScript Design Tricks
Clickable divs
Standard design practice dictates that the site logo or banner located at the top of the page links to the home page of the site. There are several methods for including such functionality into a design, including this JavaScript trick that transforms an entire element (e.g., any div) into a link pointing to the site root:
<div id="banner" onclick="location.href='/';" style="cursor:pointer;">
[ content goes here ]
</div>Hide/Validate JavaScript Code
JavaScript Comments
Commenting your scripts is an excellent and highly recommended practice. Here are two methods of commenting within a block of JavaScript.
<script type="text/javascript">
// Use two forward slashes for single line comments
/* Use this method for
multi-line comments */
</script>Link to an External JavaScript File
This is the preferred method of including JavaScript files. It is invisible to non-JavaScript browsers, and keeps the document from breaking during validation. Use if possible.
<script src="external.js" type="text/javascript"></script>Hiding JavaScript
Hiding JavaScript code from non-compliant browsers is rather easy, just employ the following lines of code:
<script type="text/javascript">
<!--
JavaScript goes here
JavaScript goes here
//-->
</script>Unfortunately, JavaScript code does not validate as XHTML. Fortunately, it is possible to present your code as invisible to the validators by enveloping it with the following lines of code:
<script type="text/javascript">
<![CDATA[
JavaScript goes here
JavaScript goes here
]]>
</script><script type="text/javascript">
<!--//--><![CDATA[//><!--
JavaScript goes here
JavaScript goes here
//--><!]]>
</script>And, an alternate method has been suggested, but sustains inconsistent consensus:
<script type="text/javascript">
/* <![CDATA[ */
JavaScript goes here
JavaScript goes here
/* ]]> */
</script>Here is the same commenting method used for CSS:
<style type="text/css">
/* <![CDATA[ */
CSS goes here
CSS goes here
/* ]]> */
</style>A slightly modified version of the previous method:
<style type="text/css">
/* //<![CDATA[ */
<!--
CSS goes here
CSS goes here
//-->
/* //]]> */
</style><style type="text/css">
<!--/*--><![CDATA[/*><!--*/
CSS goes here
CSS goes here
/*]]>*/-->
</style>Finally, although popular, avoiding this method has been recommended:
<script type="text/javascript">
//<![CDATA[
<!--
JavaScript goes here
JavaScript goes here
//-->
//]]>
</script>Non-JavaScript Browser Support
Use the <noscript> tag to provide support for antiquated browsers and serve 'em some alternate content. The <noscript> tag operates according to the presence/absence of JavaScript. Consider the following:
<noscript>
<p>This will not be displayed if JavaScript is enabled.</p>
</noscript>Here is a specific example that would provide a user with the option to continue browsing without JavaScript:
<noscript>
<p>
It appears your browser doesn't support JavaScript.
Please visit <a href="http://domain.tld/noscript.html">the no-script page</a>
to see a non-JavaScript version of this page.
</p>
</noscript>
