attach Google Analytics event tracking to all PDFs on a page

gistfile1.js

// jQuery regex filter (http://james.padolsey.com/javascript/regex-selector-for-jquery/)
jQuery.expr[':'].regex = function(elem, index, match) {
  var matchParams = match[3].split(','),
  validLabels = /^(data|css):/,
  attr = {
    method: matchParams[0].match(validLabels) ? 
                 matchParams[0].split(':')[0] : 'attr',
    property: matchParams.shift().replace(validLabels,'')
  },
  regexFlags = 'ig',
  regex = new RegExp(matchParams.join('').replace(/^\s+|\s+$/g,''), regexFlags);
  return regex.test(jQuery(elem)[attr.method](attr.property));
};

jQuery(document).ready(function($) {
  // track clicks to PDFs hosted in WordPress.
  // based on http://www.wduffy.co.uk/blog/tracking-google-goals-with-no-url-using-jquery/.
  // uses regex jQuery filter (http://james.padolsey.com/javascript/regex-selector-for-jquery/).
  $(':regex(href,(http:\/\/example\.com\/)?\/files\/.*.pdf)').click(function() {
    var re = /^(http:\/\/example\.com)?(.*)$/gi;
    var originalhref = $(this).attr('href');
    var href = originalhref.replace(re, '$2');
    console.log("PDF download at URI %s tracked with event label '%s'", originalhref, href);
    _gaq.push(['_trackEvent', 'PDF', 'download', href]);
  });
});