Change the image source on rollover using jQuery

To set up on ready:

$(function() {
    $("img")
        .mouseover(function() { 
            var src = $(this).attr("src").match(/[^\.]+/) + "over.gif";
            $(this).attr("src", src);
        })
        .mouseout(function() {
            var src = $(this).attr("src").replace("over.gif", ".gif");
            $(this).attr("src", src);
        });
});

For those that use url image sources:

$(function() {
        $("img")
            .mouseover(function() {
               var src = $(this).attr("src");
               var regex = /_normal.svg/gi;
               src = this.src.replace(regex,'_rollover.svg');
               $(this).attr("src", src);

            })
            .mouseout(function() {
               var src = $(this).attr("src");
               var regex = /_rollover.svg/gi;
               src = this.src.replace(regex,'_normal.svg');
               $(this).attr("src", src);

            });
    });

I know you're asking about using jQuery, but you can achieve the same effect in browsers that have JavaScript turned off using CSS:

#element {
    width: 100px; /* width of image */
    height: 200px; /* height of image */
    background-image: url(/path/to/image.jpg);
}

#element:hover {
    background-image: url(/path/to/other_image.jpg);
}

There's a longer description here

Even better, however, is to use sprites: simple-css-image-rollover