https://literaryballadarchive.com/wp-content/plugins/smooth-back-t…/assets/js/smooth-back-to-top-button.js

1(function ($) {
2    "use strict";
3
4    jQuery(window).on('load', function () {
5
6        var progressPath = document.querySelector('.progress-wrap path');
7        var pathLength = progressPath.getTotalLength();
8
9        progressPath.style.transition = progressPath.style.WebkitTransition = 'none';
10        progressPath.style.strokeDasharray = pathLength + ' ' + pathLength;
11        progressPath.style.strokeDashoffset = pathLength;
12        progressPath.getBoundingClientRect();
13        progressPath.style.transition = progressPath.style.WebkitTransition = 'stroke-dashoffset 10ms linear';
14
15        var updateProgress = function () {
16            var scroll = jQuery(window).scrollTop();
17            var height = jQuery(document).height() - jQuery(window).height();
18            var progress = pathLength - (scroll * pathLength / height);
19            progressPath.style.strokeDashoffset = progress;
20        };
21
22        updateProgress();
23
24        jQuery(window).scroll(updateProgress);
25
26    });
27
28})(jQuery);