jQuery.fracs determines the fraction of an HTML element that is currently in the viewport, as well as the fraction it takes of the complete viewport and the fraction of the area that might possibly be visible. It also provides the coordinates of the visible rectangle in document, element and viewport space.

It makes users easier to jump to different sections of your website. It is very suitable for one-page website or website with a lot of scrolling. jQuery.fracs is provided under the terms of the MIT License.

Requirements: jQuery Framework
Demo: http://larsjung.de/fracs/
License: MIT License