Check if Element is in view

jQuery: in view.js

var $window = $(window);
    $window_height = $window.height(),
    scrollTop = $window.scrollTop();

/**
 * Check if element visible in the viewport
 */
var aniElement = $('.animate');
var element_modifier = 0;
function checkIfInView() {
    var window_bottom_position = (scrollTop + $window_height);

    // Make them animate not when exactly on the bottom of the window
    // but move them a little higher before the animation starts.
    
    $.each(aniElement, function() {
        var el = $(this),
        element_height = el.outerHeight(),
        element_top_position = el.offset().top + element_modifier,
        element_bottom_position = (element_top_position + element_height);

        if ((element_bottom_position >= scrollTop) && (element_top_position <= window_bottom_position)) {
                el.addClass('in-view');
        } else {
            el.removeClass('in-view');
        }
    });
}

function scrollHelper(){
    scrollTop = $window.scrollTop();
    checkIfInView();
}

function resizeHelper(){
    $window_height = $window.height();
    scrollTop = $window.scrollTop();
    checkIfInView();
}

$window.on('scroll', scrollHelper);
$window.on('resize', resizeHelper);
$window.trigger('scroll');