Trigger events based on the position of the scrollbar (and visibility of elements on the page as they are scrolled into/out of view).
To use:
*Include jQuery and scrollToggle.js
//ScrollToggle(verticalScrollTriggerPosition, callbackScrolledTO, callbackScrolledAWAY)
//verticalScrollTriggerPosition can be a number, property, or computed. It is the vertical Y coord of the scrollbar destination.
var myScroller = new ScrollToggle($('#block1').position().top, function () { console.log("Element has been reached."); }, function () { console.log("Element is gone."); });
A working example can be found here: http://kroltech.com/upload/misc/scrollToggle_Sample/
A better production sample can be found here: http://www.nextgenugm.com (the orange dots in the right vertical nav change based on the sections as they scroll into view).