From 8c67e6d0f47853159c12ba6769ce9de0f77530d7 Mon Sep 17 00:00:00 2001
From: Mimi <1119186082@qq.com>
Date: Wed, 1 Jul 2020 11:29:19 +0800
Subject: [PATCH] feat: lazyload (#156)

---
 README.md       |  2 ++
 index.js        |  1 +
 lib/renderer.js |  1 +
 test/index.js   | 18 ++++++++++++++++++
 4 files changed, 22 insertions(+)

diff --git a/README.md b/README.md
index ed921e3..7b824b7 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@ marked:
   autolink: true
   sanitizeUrl: false
   headerIds: true
+  lazyload: false
   prependRoot: false
   external_link:
     enable: false
@@ -47,6 +48,7 @@ marked:
 - **autolink** - Enable autolink for URLs. E.g. `https://hexo.io` will become `<a href="https://hexo.io">https://hexo.io</a>`.
 - **sanitizeUrl** - Remove URLs that start with `javascript:`, `vbscript:` and `data:`.
 - **headerIds** - Insert header id, e.g. `<h1 id="value">text</h1>`. Useful for inserting anchor link to each paragraph with a heading.
+- **lazyload** - Lazy loading images via `loading="lazy"` attribute.
 - **prependRoot** - Prepend root value to (internal) image path.
   * Example `_config.yml`:
   ``` yml
diff --git a/index.js b/index.js
index 698f6a7..4a82c9b 100644
--- a/index.js
+++ b/index.js
@@ -14,6 +14,7 @@ hexo.config.marked = Object.assign({
   autolink: true,
   sanitizeUrl: false,
   headerIds: true,
+  lazyload: false,
   // TODO: enable prependRoot by default in v3
   prependRoot: false,
   external_link: {
diff --git a/lib/renderer.js b/lib/renderer.js
index ed8900f..0ca933d 100644
--- a/lib/renderer.js
+++ b/lib/renderer.js
@@ -93,6 +93,7 @@ class Renderer extends MarkedRenderer {
     let out = `<img src="${encodeURL(href)}"`;
     if (text) out += ` alt="${text}"`;
     if (title) out += ` title="${title}"`;
+    if (options.lazyload) out += ' loading="lazy"';
 
     out += '>';
     return out;
diff --git a/test/index.js b/test/index.js
index cd2c655..b81e7a9 100644
--- a/test/index.js
+++ b/test/index.js
@@ -573,6 +573,24 @@ describe('Marked renderer', () => {
     ].join('\n'));
   });
 
+  it('lazyload image', () => {
+    const body = [
+      '![](/bar/baz.jpg)',
+      '![foo](/aaa/bbb.jpg)'
+    ].join('\n');
+
+    ctx.config.marked.lazyload = true;
+
+    const r = require('../lib/renderer').bind(ctx);
+
+    const result = r({ text: body });
+
+    result.should.eql([
+      '<p><img src="/bar/baz.jpg" loading="lazy">',
+      '<img src="/aaa/bbb.jpg" alt="foo" loading="lazy"></p>\n'
+    ].join('\n'));
+  });
+
   describe('exec filter to extend', () => {
     it('should execute filter registered to marked:renderer', () => {
       const hexo = new Hexo(__dirname, {silent: true});