pet_effect.js

// When hovering over an anchor
// find all anchors with the same href attribute
// and give them all a 'hover' class

;(function(_){
  jQuery.fn.extend({
    attrSelector: function(attr) {
      return '['
           + attr
           + '="'
           + this.attr(attr)
           + '"]';
    },
    
    matchingAttribute: function(attr) {
      return $(this.attrSelector(attr));
    }
  });

  _(function() {
    _('a').hover(
      function(){
        _(this).matchingAttribute('href').addClass('hover');
      }
      ,function() {
        _(this).matchingAttribute('href').removeClass('hover');
      }
    );
  });
})(jQuery);