https://www.ellenhealth.com.au/wp-content/themes/duxdigital/plugins/jquery.visible.js?ver=7.0.2

1(function ($) {
2
3  /**
4   * Copyright 2012, Digital Fusion
5   * Licensed under the MIT license.
6   * http://teamdf.com/jquery-plugins/license/
7   *
8   * @author Sam Sehnert
9   * @desc A small plugin that checks whether elements are within
10   *     the user visible viewport of a web browser.
11   *     only accounts for vertical position, not horizontal.
12   */
13
14  $.fn.visible = function (partial) {
15    if (this.length > 0) {
16      var $t = $(this),
17        $w = $(window),
18        viewTop = $w.scrollTop(),
19        viewBottom = viewTop + $w.height(),
20        _top = $t.offset().top,
21        _bottom = _top + $t.height(),
22        compareTop = partial === true ? _bottom : _top,
23        compareBottom = partial === true ? _top : _bottom;
24
25      return ((compareBottom <= viewBottom) && (compareTop >= viewTop));
26    }
27  };
28
29})(jQuery);