HMTL image maps & preloading images

Question

I've built quite a large old school HTML image map. When you mouseover an area tag, another image is loaded that replaces the entire map. In all there are 30 some mouseover images and to avoid the delay in loading I've preloaded them using jQuery.

Firebug Net panel shows all images are being loaded ok at pageload (no mouseover triggered yet). Now, when I mouseover an area, firebug shows this image is being request a second time. This despite the fact I clearly see the filename a few lines higher up in firebug.

Is this normal behavior? It seems preloading works ... but the mouseover still sends a request to the server to get the image resulting in a 1-2 sec delay before the images swap.

This is all straight html, no AJAX involved.

Thx

Answer 1

You probably need to tweak the caching configuration on your web server so that the browser knows not to redownload the images.

Answer 2

Do you see the 1-2 second delay when Firebug is not open? I've had similar issues and could never really tell if it was actually requesting the image again. I wouldn't see a new request when tailing my logs either. Also, I never saw this behavior when looking through the Safari inspector so I chalked it up to Firebug.