Fire event when div is visible to visitor with jQuery?

Question

The function: I want to change the class of a certain item when a user see a certain div (scrolls down to it).

How I do it now: I\'

Answer 1

This would probably be useful for you.

Anyhow, you could probably do it without a plug-in and with a simple expression instead:

var elem_top    = $("some_element").offset().top;
var elem_height = $("some_element").height();
var wind_height = $(window).height();
var scrollTop   = $(window).scrollTop;

if (elem_top > (wind_height + scrollTop) &&
   !(elem_top + elem_height) < wind_scrollTop) 
{
    //The element is inside the screen (e.g. it is directly visible)
}