Apply JavaScripts Wisely

JavaScripts can be included in an (X)HTML document in any of four ways:

  • In an external file

  • Between a pair of <script>...</script> tags

  • In an event handler

  • After the javascript: pseudo-protocol in an URL

Let's use our minimal Mondrian to demonstrate them all:

 <!DOCTYPE html       PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"      ""> <html xmlns="" xml:lang="en" lang="en"> <head> <title>Piet Mondrian's Home Page</title> <script src="/scripts/foo.js" defer="defer" type="text/javascript"></script> <script type="text/javascript">       var foo = 1; </script> </head> <body>       <h1>Piet Mondrian: Abstract Impressionist</h1>       <p>Mondrian was one of the great abstract masters...</p>       <p><a onmouseover="window.status='Mondrian Home Page'; return true;"; href="http:// graphics/ccc.gif"></a></p> <p><a href="'')"></a></p> </body> </html> 

In honor of Mondrian and expediency, let's focus squarely on the first two options. Event handlers can be used to link behavior to elements ( ideally with functions), but the javascript: pseudo-protocol should be avoided as the only reference of a link. The 11 percent of people without JavaScript won't be able to access this content. [3] This is not exactly user friendly. [4] A number of sites rely on JavaScripteven government sites that should be easily accessible like

[3], "JavaScript Stats," in Global Statistics 2002 [online], (Darien, CT: Jupitermedia Corporation, October, 2002), available from the Internet at http://www. thecounter .com/stats/.
[4] Pamela L. O'Connell, "Site Unseen?," New York Times , 14 February 2002, Circuits section, D3. Shirley Kaiser of and I were quoted in this story about, a site that required JavaScript.

Here's the syntax of the script element:

Function: Defines an executable script
Attributes: CHARSET , DEFER , LANGUAGE(deprecated) , SRC , TYPE
 <script type="text/javascript" src="/scripts/foo.js"></script> <script type="text/javascript" src="/f.js" defer="defer"></script> /* optimized */ 
End tag: </script> , not optional
Alternate: <noscript>alternate content</noscript>
Used in: <head> , <body>


Speed Up Your Site[c] Web Site Optimization
Speed Up Your Site[c] Web Site Optimization
ISBN: 596515081
Year: 2005
Pages: 135 © 2008-2017.
If you may any questions please contact us: