Replacing only part of an iframe src
<p>I need to use javascript to change part of an iframe src, is there a way to change '500' to '800' in that iframe src? I tried the following code but it did not work. If anyone could help that'd be appreciated.</p>

<pre><code>        function bigPhotosets() {
            $('iframe.photoset').each(function(){
                $(this).attr('src').replace('500','800');
                $(this).attr('width').replace('500','800');
            });
        }

        bigPhotosets();
</code></pre>
