https://www.promityatsugi.com/wp/wp-content/themes/mutation/js/jquery.scrolly.js?ver=6.5.12

1/*
2 *  Project: Scrolly : parallax is easy as a matter of fact !
3 *  Description: Based on jQuery boilerplate
4 *  Author: Victor C. / Octave & Octave web agency
5 *  Licence: MIT
6 */
7!function(root, factory) {
8  if (typeof define === 'function' && define.amd) {
9    define(['jquery'], factory);
10  } else {
11    factory(root.jQuery);
12  }
13}(this, function($) {
14  'use strict';
15
16  // Create the defaults once
17  var pluginName = 'scrolly',
18  defaults = {
19    bgParallax: false
20  },
21  didScroll = false;
22
23  function Plugin( element, options ) {
24    this.element = element;
25    this.$element = $(this.element);
26
27    this.options = $.extend( {}, defaults, options) ;
28
29    this._defaults = defaults;
30    this._name = pluginName;
31
32    this.init();
33  }
34
35  Plugin.prototype.init = function () {
36    var self = this;
37    this.startPosition = this.$element.position().top;
38    this.offsetTop = this.$element.offset().top;
39    this.height = this.$element.outerHeight(true);
40    this.velocity = this.$element.attr('data-velocity');
41    this.bgStart = parseInt(this.$element.attr('data-fit'), 10);
42
43    $(document).scroll(function(){
44      self.didScroll = true;
45    });
46
47    setInterval(function() {
48      if (self.didScroll) {
49        self.didScroll = false;
50        self.scrolly();
51      }
52    }, 10);
53  };
54
55  Plugin.prototype.scrolly = function() {
56    var dT =  $(window).scrollTop(),
57    wH = $(window).height(),
58    position = this.startPosition;
59
60    if(this.offsetTop >= (dT+wH)) {
61      this.$element.addClass('scrolly-invisible');
62    } else {
63      if(this.$element.hasClass('scrolly-invisible')){
64        position = this.startPosition + (dT + ( wH - this.offsetTop ) ) * this.velocity;
65      } else {
66        position = this.startPosition + dT  * this.velocity;
67      }
68    }
69    // Fix background position
70    if(this.bgStart){ position = position + this.bgStart; }
71
72    if(this.options.bgParallax === true) {
73      this.$element.css({backgroundPosition: '50% '+position+'px'});
74    } else {
75      this.$element.css({top: position});
76    }
77  };
78
79  $.fn[pluginName] = function ( options ) {
80    return this.each(function () {
81      if (!$.data(this, 'plugin_' + pluginName)) {
82        $.data(this, 'plugin_' + pluginName, new Plugin( this, options ));
83      }
84    });
85  };
86
87});