jQuery rollovers using multiple ids and classes

<img src='' class='apple fruit red' />

$(".apple").mouseover(function() {
   $(".apple").addClass("overState");
});

<img src="the-big-red-apple.jpg" class="tagged tag-big tag-red tag-apple" />

$('img.tagged')
    .each(function() {
        var thisClasses = this.className.split(/s+/); // array of classes.
        var search = [];
        for (var i = 0; i < thisClasses.length; ++i) {
            if (thisClasses[i].substr(0, 4) == "tag-") {
                search.push("." + thisClasses[i]);
            }
        }
        $(this).data("tags", search.join(","));  // ".tag-big,.tag-red,.tag-apple"
    })
    .hover(function() {
        $('img.tagged')
            .filter(this.data('tags'))
            .addClass("highlight")
        ;
    }, function() {
        $('img.tagged')
            .filter(this.data('tags'))
            .removeClass("highlight")
        ;
    })
;

function swapImageGroup(imgSelector,suffix){
if (suffix == null) {suffix = "-hover";}
//imgSelector is the jQuery selector to use
//both imgSelector and suffix must be strings
$(selector).hover(
   function() {
      $(selector).each(function(){
      //store ".jpg" or ".png" or whatever as fileExtension
      var fileExtension = $(this).attr("src").substr($(this).attr("src").lastIndexOf("."));
      //replace something like ".jpg" with something like "-hover.jpg",
      //assuming suffix == "-hover"
      $(this).attr("src", $(this).attr("src").replace(fileExtension, suffix + fileExtension));
    });
    },
    function() {
      $(selector).each(function(){
      //chop off the end of the filename, starting at "-hover" (or whatever)
      //and put the original extension back on
      $(this).attr("src", $(this).attr("src").split(suffix + ".").join("."));
      });
    }
);
}

swapImageGroup("img.apple");

swapImageGroup("img.foo","-active");

a.apple:hover img {
  /* whatever you want to change here */
}