Footnotify click handler (excerpt for a blog post)

footnotify-click-handler.js

// Click handler below taken from lines 179-213 of footnotify.js
// in this Gist: <https://gist.github.com/2793552>

$("a").click(function(event){
  var target = $(event.currentTarget),
      href = target.attr('href'),
      selector, footnote_el, text;
      
  if (href) {
    switch (0) {
      case href.indexOf(location.pathname):
      case href.indexOf(location.origin + location.pathname):
        href = href.replace(/^(.+)(\#.+)$/, '$2');
        // fall through:
      case href.indexOf('#'):
        selector = '#'+href.substr(1).replace(selectorRegExp,'\\$&');
        
        footnote_el = $(selector);            
        text = target.text();
        
        //consider validate on contents of text (instead of testing for subscript).      

        //Target was not in superscript.
        if (!target.parents().is("sup")) { return null; }
        //No target.
        if (footnote_el.length === 0) { return null; }        
        //Have no children paragraphs, and is not a list element
        if (footnote_el.children('p').length === 0 && footnote_el.filter('li').length === 0) { return null; }
        //Contains images so it's probably not a footnote.
        if (footnote_el.find('img').length > 0) { return null; } 

        return footnote_el;
      // no default
    }
  }
  
  return null;    
});