Check if element is visible in div

Question

I have a div with many li's inside.

<div>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
...
</div>

Typically when the user is scrolling inside the window, some <li>'s get into the overflow and will be hidden. I know I can check if an element is in the viewport of the screen with this jQuery Plugin: http://www.appelsiini.net/projects/viewport I would just need this functionality, but not for the whole screen, but on a single div only. So I could update some text when elements aren't visible.

Need some help, Thanks in advance!

Answer 1

This is a very good answer, but here's a modified version of the Viewport plugin you mentioned.

(function($) {

$.belowthefold = function(lookIn, elements, settings) {
    var fold = $(lookIn).height() + $(lookIn).scrollTop();
    return $(elements).filter(function(){
        return fold <= $(this).offset().top - settings.threshold;
    });
};

$.abovethetop = function(lookIn, elements, settings) {
    var top = $(lookIn).scrollTop();
    return $(elements).filter(function(){
        return top >= $(this).offset().top + $(this).height() - settings.threshold;
    });
};

$.rightofscreen = function(lookIn, elements, settings) {
    var fold = $(lookIn).width() + $(lookIn).scrollLeft();
    return $(elements).filter(function(){
        return fold <= $(this).offset().left - settings.threshold;
    });
};

$.leftofscreen = function(lookIn, elements, settings) {
    var left = $(lookIn).scrollLeft();
    return $(elements).filter(function(){
        return left >= $(this).offset().left + $(this).width() - settings.threshold;
    });
};

})(jQuery);

With HTML like this:

<div id="lookInMe">
    <div class="peek"></div>
    <div class="peek"></div>
    [ ... ]
</div>

Call it like this:

$.belowthefold("#lookInMe", ".peek", {threshold : 0}).text("Below");
$.abovethetop("#lookInMe", ".peek", {threshold : 0}).text("Above");
$.leftofscreen("#lookInMe", ".peek", {threshold : 0}).text("Left");
$.rightofscreen("#lookInMe", ".peek", {threshold : 0}).text("Right");

http://jsfiddle.net/daCrosby/vhF7x/1/