https://www.remotepanda.com/wp-content/themes/startit/assets/js/modules/plugins/parallax.min.js

1/*
2 Plugin: jQuery Parallax
3 Version 1.1.3
4 Author: Ian Lunn
5 Twitter: @IanLunn
6 Author URL: http://www.ianlunn.co.uk/
7 Plugin URL: http://www.ianlunn.co.uk/plugins/jquery-parallax/
8
9 Dual licensed under the MIT and GPL licenses:
10 http://www.opensource.org/licenses/mit-license.php
11 http://www.gnu.org/licenses/gpl.html
12 */
13
14(function( $ ){
15    "use strict";
16
17    var $window = $(window);
18    var windowHeight = $window.height();
19
20    $window.resize(function () {
21        windowHeight = $window.height();
22    });
23
24    $.fn.parallax = function(xpos, speedFactor, outerHeight) {
25        var $this = $(this);
26        var getHeight;
27        var firstTop;
28        var paddingTop = 0;
29
30        //get the starting position of each element to have parallax applied to it
31        $this.each(function(){
32            firstTop = $this.offset().top;
33        });
34
35        if (outerHeight) {
36            getHeight = function(jqo) {
37                return jqo.outerHeight(true);
38            };
39        } else {
40            getHeight = function(jqo) {
41                return jqo.height();
42            };
43        }
44
45        // setup defaults if arguments aren't specified
46        if (arguments.length < 1 || xpos === null) xpos = "50%";
47        if (arguments.length < 2 || speedFactor === null) speedFactor = 0.1;
48        if (arguments.length < 3 || outerHeight === null) outerHeight = true;
49
50        // function to be called whenever the window is scrolled or resized
51        function update(){
52            var pos = $window.scrollTop();
53
54            $this.each(function(){
55                var $element = $(this);
56                var top = $element.offset().top;
57                var height = getHeight($element);
58
59                // Check if totally above or totally below viewport
60                if (top + height < pos || top > pos + windowHeight) {
61                    return;
62                }
63
64                $this.css('backgroundPosition', xpos + " " + Math.round((firstTop - pos) * speedFactor) + "px");
65            });
66        }
67
68        $window.bind('scroll', update).resize(update);
69        update();
70    };
71})(jQuery);