https://www.pioneersacademy.com/Content/js/angular/directives/loading_directive.js

1app.directive('pioLoading', ['$timeout', function ($timeout) {
2    return {
3        restrict: 'A',
4        link: function (scope, element, attrs) {
5            var host = element[0];
6            var reserved = (attrs.pioLoadingHeight || '').trim();
7            var holdsHeight = attrs.pioLoadingHold !== 'false';
8            var overlay = document.createElement('div');
9            var lastHeight = 0;
10            var observer = null;
11
12            overlay.className = 'pio-loading-overlay';
13            overlay.setAttribute('aria-hidden', 'true');
14            overlay.innerHTML = '<span class="pio-loading-spinner"></span>';
15
16            host.classList.add('pio-loading-host');
17            if (reserved) host.style.minHeight = reserved;
18            host.appendChild(overlay);
19
20            function remember() {
21                if (host.classList.contains('pio-is-loading')) return;
22                var height = host.offsetHeight;
23                if (height > 0) lastHeight = height;
24            }
25
26            if (window.ResizeObserver) {
27                observer = new ResizeObserver(remember);
28                observer.observe(host);
29            }
30
31            function hold() {
32                if (!observer) remember();
33                if (holdsHeight && lastHeight > 0) host.style.minHeight = lastHeight + 'px';
34                host.classList.add('pio-is-loading');
35                host.setAttribute('aria-busy', 'true');
36            }
37
38            function release() {
39                host.classList.remove('pio-is-loading');
40                host.removeAttribute('aria-busy');
41                host.style.minHeight = reserved;
42                $timeout(remember, 0, false);
43            }
44
45            scope.$watch(
46                function () { return !!scope.$eval(attrs.pioLoading); },
47                function (loading) { if (loading) hold(); else release(); }
48            );
49
50            scope.$on('$destroy', function () {
51                if (observer) observer.disconnect();
52            });
53        }
54    };
55}]);