https://www.springerpub.com/static/version1789146322/base/Magento/base/default/jquery/z-index.js

1/*!
2 * zIndex plugin from jQuery UI Core - v1.10.4
3 * http://jqueryui.com
4 *
5 * Copyright 2014 jQuery Foundation and other contributors
6 * Released under the MIT license.
7 * http://jquery.org/license
8 *
9 * http://api.jqueryui.com/category/ui-core/
10 */
11define([
12    'jquery'
13], function ($, undefined) {
14
15// plugins
16    $.fn.extend({
17        zIndex: function (zIndex) {
18            if (zIndex !== undefined) {
19                return this.css("zIndex", zIndex);
20            }
21
22            if (this.length) {
23                var elem = $(this[0]), position, value;
24                while (elem.length && elem[0] !== document) {
25                    // Ignore z-index if position is set to a value where z-index is ignored by the browser
26                    // This makes behavior of this function consistent across browsers
27                    // WebKit always returns auto if the element is positioned
28                    position = elem.css("position");
29                    if (position === "absolute" || position === "relative" || position === "fixed") {
30                        // IE returns 0 when zIndex is not specified
31                        // other browsers return a string
32                        // we ignore the case of nested elements with an explicit value of 0
33                        // <div style="z-index: -10;"><div style="z-index: 0;"></div></div>
34                        value = parseInt(elem.css("zIndex"), 10);
35                        if (!isNaN(value) && value !== 0) {
36                            return value;
37                        }
38                    }
39                    elem = elem.parent();
40                }
41            }
42
43            return 0;
44        }
45    });
46});