Interactive online maps are frequently done in Flash. That’s a problem if you’re using a device that doesn’t support Flash, like an iPhone or iPad. Andrew Long discusses using a jQuery plugin — JavaScript instead of Flash — to create a before/after map that uses a slider to swipe between two different images. Oliver O’Brien uses the technique with aerial photos of London (see also). It’ll be interesting to see whether other maps will get their interactivity through HTML5, CSS3 and JavaScript instead of Flash. Via @desjardins and GIS Lounge.