From 7aa203150fc1a2ec79c681c13f0d486d531746eb Mon Sep 17 00:00:00 2001
From: George Halkiadakis <gchalkiadakis@sklavenitis.co.gr>
Date: Sun, 12 Mar 2023 23:57:48 +0200
Subject: error pages; js system to support back/front-end

---
 html/assets/js/images/lazyload.js | 61 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 html/assets/js/images/lazyload.js

(limited to 'html/assets/js/images')

diff --git a/html/assets/js/images/lazyload.js b/html/assets/js/images/lazyload.js
new file mode 100644
index 0000000..4f954af
--- /dev/null
+++ b/html/assets/js/images/lazyload.js
@@ -0,0 +1,61 @@
+$$plugins.define('lazyload', function (element, options) {
+    const plugin = this;
+    plugin.logger.debug("lazy loading");
+    const mutationObserver =
+            new MutationObserver(function (mutations) {
+                mutations.forEach(function (mutation, index) {
+                    if (mutation.type === 'childList') {
+                        mutation.addedNodes.forEach(update);
+                    }
+                });
+            }),
+        observer =
+            new IntersectionObserver(function (entries, self) {
+                entries.forEach(function (entry) {
+                    if (entry.isIntersecting) {
+                        load(entry.target);
+                        self.unobserve(entry.target);
+                    }
+                });
+            }, options || {
+                rootMargin: '0px 0px 1250px 0px',
+                threshold: 0
+            }),
+        elms = element.querySelectorAll('.lazy');
+    elms.forEach(elm => observer.observe(elm));
+    mutationObserver.observe(element, { childList: true, subtree: true });
+
+    function update(element) {
+        if (!(element instanceof (HTMLElement))) {
+            return;
+        }
+        const container = element || document;
+        if (!container.querySelectorAll) {
+            return;
+        }
+        const elms = container.querySelectorAll('.lazy');
+        Array.prototype.forEach.call(elms, (elm) => !elm.getAttribute('data-loaded') && observer.observe(elm));
+    }
+
+    function load(elm) {
+        let i = 0, source, attr, picture = elm.parentElement, sources = picture.querySelectorAll('.lazysrcset');
+        if (sources.length) {
+            for (; i < sources.length; i++) {
+                source = sources[i];
+                attr = source.getAttribute('data-srcset');
+                if (attr) {
+                    source.srcset = source.getAttribute('data-srcset');
+                }
+            }
+        }
+
+        if (!elm.getAttribute('data-loaded') && elm.getAttribute('data-src')) {
+            elm.src = elm.getAttribute('data-src');
+            elm.setAttribute('data-loaded', true);
+        }
+    }
+
+    return {
+        update: update
+    };
+});
\ No newline at end of file
-- 
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