You use CSS and templates to setup navigation menus with fluid links. You would use jQuery/AJAX to change values of components on-the-fly. For example, you have a drop-down menu with an onChange() event that calls JS with jQuery. If it's a dynamic request, you could pull it back with AJAX fed with JSON (or AJAX, whatever floats your boat). That comes back and changes the value of another textbox on the page (without reloading). You wouldn't use that for an entire navigation menu.
If I'm understanding what you're asking, anyway.
If I'm understanding what you're asking, anyway.
