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

to judge the div is visible or not, you can:

$(window).scroll(function(event) {
    console.log($(".target").offset().top < $(window).scrollTop() + $(window).outerHeight());
});

so, i don't think you need any plugin.

just judge it by the expression like:

if($(".target").offset().top < $(window).scrollTop() + $(window).outerHeight()) {
    // something when the .target div visible
} else {
    // something when the .target div invisible
}