Close a popup if element is scrolled into view, reopen when it goes offscreen.

close-popup-when-element-is-scrolled-into-view.js

var was_closed = false;

jQuery(window).on('scroll', function () {
    var footer = jQuery('#footer'),
          footer_is_visible = footer.offset().top - jQuery(window).scrollTop() < footer.height(),
          popup = PUM.getPopup(123),
          popup_is_open = popup.hasClass('pum-active');

    if (popup_is_open  && footer_is_visible) {
        PUM.close(123);
        was_closed = true;
    } elseif (was_closed && !footer_is_visible && !popup_is_open) {
        PUM.open(123);
        was_closed = false;
    }
});