From 9faea274db0cd42959ff4823eb4e61e048bb7677 Mon Sep 17 00:00:00 2001
From: Eltrac <hi@guhub.cn>
Date: Mon, 31 Mar 2025 11:18:22 +0800
Subject: refactor: automatic and native lazyload

- replace vanilla-lazyload with native `loading="lazy"` method
- prettify code


Former-commit-id: 3c391ba20d3d8346790b62a7c62f3b0a008d08fa
---
 hugo.yaml                     |  25 +++++-----
 layouts/partials/scripts.html | 113 ++++++++++++++++++++++++++++--------------
 2 files changed, 88 insertions(+), 50 deletions(-)

diff --git a/hugo.yaml b/hugo.yaml
index 297c2c5c..feb518ca 100644
--- a/hugo.yaml
+++ b/hugo.yaml
@@ -15,18 +15,18 @@ languages:
     params:
       headTitle: 極客死亡計劃
       nav:
-      - name: 卡片
-        link: /cards/
-        target: _self
-      - name: 书籍
-        link: /library/
-        target: _self
-      - name: 分类
-        link: /categories/
-        target: _self
-      - name: 关于
-        link: /about/
-        target: _self
+        - name: 卡片
+          link: /cards/
+          target: _self
+        - name: 书籍
+          link: /library/
+          target: _self
+        - name: 分类
+          link: /categories/
+          target: _self
+        - name: 关于
+          link: /about/
+          target: _self
       series:
         - name: 人类恶疾
           link: /categories/人类恶疾/
@@ -85,7 +85,6 @@ params:
   extraCSSFiles:
     - /pagefind/pagefind-ui.css
   externalJSFIles:
-    - https://unpkg.com/vanilla-lazyload@19.1.3/dist/lazyload.min.js
     - https://unpkg.com/@fancyapps/ui@5.0.36/dist/fancybox/fancybox.umd.js
     - https://unpkg.com/littlefoot/dist/littlefoot.js
     - /pagefind/pagefind-ui.js
diff --git a/layouts/partials/scripts.html b/layouts/partials/scripts.html
index 7218ee86..bd6002b1 100644
--- a/layouts/partials/scripts.html
+++ b/layouts/partials/scripts.html
@@ -3,43 +3,82 @@
 <script src="{{ $.Site.Params.staticPrefix }}{{ . | relURL }}"></script>
 {{- end }}
 <script type="module">
-/* === lazyload === */
-var lazyLoadInstance = new LazyLoad();
-lazyLoadInstance.update();
-
-/* === Fancybox === */
-document.addEventListener("DOMContentLoaded", function () {
-    document.querySelectorAll(".markdown-body img:not(figure img, .no-fancybox)").forEach(img => {
-        if (img.closest("figure")) return; // 跳过已经在 <figure> 内的 <img>
-
-        let src = img.getAttribute("src");
-        let alt = img.getAttribute("alt") || ""; // 获取 alt 作为 title
-
-        // 创建 <a> 标签包裹 <img>
-        let link = document.createElement("a");
-        link.setAttribute("href", src);
-        link.setAttribute("data-fancybox", "gallery"); // Fancybox 组
-        link.setAttribute("data-caption", alt); // 设置 title
-        link.setAttribute("aria-label", alt); // 辅助功能优化
-
-        // 创建 <figcaption> 并添加 <h4>
-        let figcaption = document.createElement("figcaption");
-        let captionTitle = document.createElement("h4");
-        captionTitle.textContent = alt;
-        figcaption.appendChild(captionTitle);
-
-        // 创建 <figure> 并包裹 <a> + <figcaption>
-        let figure = document.createElement("figure");
-        figure.appendChild(link);
-        figure.appendChild(figcaption);
-
-        // 替换原始 img
-        img.parentNode.insertBefore(figure, img);
-        link.appendChild(img); // 将 img 插入 <a>
+    /* === lazyload === */
+    document.addEventListener("DOMContentLoaded", () => {
+        const allImages = document.querySelectorAll("img");
+        const images = document.querySelectorAll("img[data-src]");
+
+        const loadImage = (image) => {
+            const loadingImage = image.src; // Store current loading image (if any)
+            const realImage = image.dataset.src; // Get the real image URL from data-src
+            image.src = loadingImage; // Optionally, reset the src to the placeholder
+            image.onload = () => {
+                image.classList.add("fade-in"); // Optional: Apply fade-in effect after loading
+            };
+            image.src = realImage; // Now, load the actual image
+            image.removeAttribute("data-src"); // Clean up after lazy loading
+        };
+
+        const observer = new IntersectionObserver(
+            (entries, observer) => {
+                entries.forEach((entry) => {
+                    if (entry.isIntersecting) {
+                        loadImage(entry.target);
+                        observer.unobserve(entry.target); // Stop observing once the image has loaded
+                    }
+                });
+            },
+            { threshold: 0.1 },
+        );
+
+        // initialize native lazyloading
+        allImages.forEach((img) => {
+            img.setAttribute("loading", "lazy");
+        });
+
+        // lazy load
+        images.forEach((image) => {
+            observer.observe(image); // Start observing each image
+        });
+    });
+
+    /* === Fancybox === */
+    document.addEventListener("DOMContentLoaded", function () {
+        document
+            .querySelectorAll(
+                ".markdown-body img:not(figure img, .no-fancybox)",
+            )
+            .forEach((img) => {
+                if (img.closest("figure")) return; // 跳过已经在 <figure> 内的 <img>
+
+                let src = img.getAttribute("src");
+                let alt = img.getAttribute("alt") || ""; // 获取 alt 作为 title
+
+                // 创建 <a> 标签包裹 <img>
+                let link = document.createElement("a");
+                link.setAttribute("href", src);
+                link.setAttribute("data-fancybox", "gallery"); // Fancybox 组
+                link.setAttribute("data-caption", alt); // 设置 title
+                link.setAttribute("aria-label", alt); // 辅助功能优化
+
+                // 创建 <figcaption> 并添加 <h4>
+                let figcaption = document.createElement("figcaption");
+                let captionTitle = document.createElement("h4");
+                captionTitle.textContent = alt;
+                figcaption.appendChild(captionTitle);
+
+                // 创建 <figure> 并包裹 <a> + <figcaption>
+                let figure = document.createElement("figure");
+                figure.appendChild(link);
+                figure.appendChild(figcaption);
+
+                // 替换原始 img
+                img.parentNode.insertBefore(figure, img);
+                link.appendChild(img); // 将 img 插入 <a>
+            });
     });
-});
-Fancybox.bind("[data-fancybox]");
+    Fancybox.bind("[data-fancybox]");
 
-/* === littlefoot === */
-littlefoot.littlefoot(littlefootOptions)
+    /* === littlefoot === */
+    littlefoot.littlefoot(littlefootOptions);
 </script>
-- 
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