From de36083b9f08f1549a8f25578b2854d8aeecc388 Mon Sep 17 00:00:00 2001
From: Benjamin Schaaf <ben.schaaf@gmail.com>
Date: Tue, 21 Jul 2026 13:16:57 +1000
Subject: [PATCH] Avoid re-rendering readmes

The readme rendering is slow and memory intensive, but there's no reason
to redo all that work every time. We now store a hash of the text used
to render the readme inside readmes_renderes.json to avoid re-rendering.
---
 eleventy.config.mjs |  2 +-
 render_readmes.mjs  | 11 ++++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/eleventy.config.mjs b/eleventy.config.mjs
index 731a27ed0..6d654785e 100644
--- a/eleventy.config.mjs
+++ b/eleventy.config.mjs
@@ -598,7 +598,7 @@ export default async function (eleventyConfig) {
       installed: stat?.installs?.totals ?? 0,
       installs_window: stat?.installs?.yearly?.reduce((a, b) => a + b, 0) ?? 0,
       ...(readme_url !== pkg.readme ? { readme_url } : {}),
-      ...(renderedReadmes[pkg.readme] ? { rendered_readme: renderedReadmes[pkg.readme] } : {}),
+      ...(renderedReadmes[pkg.readme] ? { rendered_readme: renderedReadmes[pkg.readme][1] } : {}),
       ...(source_url !== pkg.source ? { source_url } : {}),
     }
   }
diff --git a/render_readmes.mjs b/render_readmes.mjs
index 4716c177c..b3ff1b838 100644
--- a/render_readmes.mjs
+++ b/render_readmes.mjs
@@ -5,22 +5,31 @@ import { JSDOM } from 'jsdom'
 import createDOMPurify from 'dompurify'
 import { marked } from 'marked'
 import { configureMarked, renderReadme } from './static/readme-renderer.mjs'
+import { createHash } from 'crypto'
 
 const args = parseArgs(process.argv.slice(2))
 const rawReadmes = readJson(args.input)
 const dom = new JSDOM('')
 const DOMPurify = createDOMPurify(dom.window)
 const parser = new dom.window.DOMParser()
+
+const oldRenderedReadmes = readJson(args.output)
 const renderedReadmes = {}
 
 configureMarked(marked)
 
 for (const [url, text] of Object.entries(rawReadmes)) {
+  const hash = createHash('sha256').update(text).digest('base64')
+  if (oldRenderedReadmes[url] && oldRenderedReadmes[url][0] === hash) {
+    renderedReadmes[url] = [hash, oldRenderedReadmes[url][1]]
+    continue
+  }
+
   const html = renderReadme(marked, text, url, {
     sanitize: html => DOMPurify.sanitize(html),
     parseHtml: html => parser.parseFromString(html, 'text/html'),
   })
-  renderedReadmes[url] = html
+  renderedReadmes[url] = [hash, html]
 }
 
 fs.writeFileSync(args.output, JSON.stringify(renderedReadmes, null, 2) + '\n')