Embed a React Widget in a Blog Post

Build a React (JSX) component into a single self-contained HTML file and embed it in a Jekyll/Chirpy blog post via iframe.

Key Constraints

• Jekyll processes all .html files through Liquid. Files without front matter are treated as static files and copied as-is — this is what we want. Never add YAML front matter or {% raw %} tags to widget HTML files.
• Minified JS often contains template-literal syntax (${...}, backticks) that Liquid interprets as tags, causing builds to hang indefinitely. The solution is to let the file be a static file (no front matter = no Liquid processing).
• Build time: Jekyll takes ~60 seconds on this repo. That's normal, not a hang. Wait for it.
• Never put node_modules inside the blog repo. Jekyll copies all static files under assets/ — thousands of files from node_modules will make builds take 10+ minutes. The exclude config in _config.yml does NOT prevent static files under assets/ from being copied.

Build Location

Keep the widget build project permanently at C:\Users\kkanjitajdin\widget-builds\<widget-name>\ — outside the blog repo. This folder keeps node_modules installed so rebuilds are fast (~25s instead of 2+ minutes for npm install + build).

C:\Users\kkanjitajdin\widget-builds\<widget-name>\
├── package.json
├── vite.config.js
├── index.html
├── node_modules/          ← stays permanently, no reinstall needed
└── src/
    ├── main.jsx
    ├── index.css
    ├── App.jsx            ← copy of the source .jsx from blog assets
    └── components/ui/     ← inline shadcn/ui components if needed

The source .jsx lives in the blog repo at assets/posts/<post-slug>/WidgetName.jsx. Edit it there, then copy to the build folder to rebuild.

2. Key dependencies

{
  "dependencies": {
    "preact": "^10.25.0",
    "lucide-react": "^0.475.0"
  },
  "devDependencies": {
    "@preact/preset-vite": "^2.9.0",
    "vite": "^6.0.0",
    "vite-plugin-singlefile": "^2.0.0",
    "tailwindcss": "^4.0.0",
    "@tailwindcss/vite": "^4.0.0"
  }
}

vite-plugin-singlefile is essential — it inlines all JS and CSS directly into the HTML output. Without it, Vite produces separate .js and .css files that won't load inside an iframe served from a different path.

Use Preact, not React — Preact is a 3KB drop-in replacement for React (140KB). Same JSX, same hooks. The @preact/preset-vite plugin aliases react and react-dom to preact/compat automatically, so libraries like lucide-react work unchanged.

Do not use framer-motion — it adds ~150KB for animations that CSS transitions handle in 3 lines. Use CSS @keyframes instead.

3. Vite config

import { defineConfig } from 'vite'
import preact from '@preact/preset-vite'
import tailwindcss from '@tailwindcss/vite'
import { viteSingleFile } from 'vite-plugin-singlefile'
import { resolve } from 'path'

export default defineConfig({
  plugins: [preact(), tailwindcss(), viteSingleFile()],
  resolve: {
    alias: { '@': resolve(__dirname, 'src') },
  },
  build: { outDir: 'dist' },
})

3b. Entry point (src/main.jsx)

import { render } from "preact";
import App from "./App.jsx";
import "./index.css";

render(<App />, document.getElementById("root"));

4. Handle shadcn/ui imports

The source .jsx likely imports from @/components/ui/card, @/components/ui/button, etc. These are shadcn/ui components that need to be inlined since you can't install the full library in a standalone build.

Create a single file src/components/ui/card.jsx that exports all needed components (Card, CardHeader, CardTitle, CardContent, Badge, Button, Separator) as minimal Tailwind-styled React components.

Then rewrite the import in App.jsx:

// Before (multiple shadcn imports):
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Badge } from "@/components/ui/badge";
import { Separator } from "@/components/ui/separator";

// After (single import):
import { Card, CardContent, CardHeader, CardTitle, Badge, Button, Separator } from "@/components/ui/card";

5. Build and deploy

# From the permanent build folder (not the blog repo)
cd C:\Users\kkanjitajdin\widget-builds\<widget-name>

# Copy latest source from blog repo
Copy-Item "C:\Users\kkanjitajdin\mcscatblog\assets\posts\<post-slug>\WidgetName.jsx" "src\App.jsx" -Force

# Fix shadcn imports (if source still has separate imports)
(Get-Content "src\App.jsx" -Raw) -replace 'import \{ Card.*\} from "@/components/ui/card";[\s\S]*?import \{ Separator \} from "@/components/ui/separator";', 'import { Card, CardContent, CardHeader, CardTitle, Badge, Button, Separator } from "@/components/ui/card";' | Set-Content "src\App.jsx" -Encoding utf8

# Build (fast — node_modules already installed)
npm run build
# Output: dist/index.html (single file, ~370KB)

# Copy built HTML back to blog repo assets
Copy-Item "dist\index.html" "C:\Users\kkanjitajdin\mcscatblog\assets\posts\<post-slug>\WidgetName.html" -Force

No need to delete anything — the build folder is outside the blog repo and doesn't affect Jekyll.

6. Embed in the blog post

Use an iframe with relative_url for the baseurl prefix:

<iframe src="{{ '/assets/posts/<post-slug>/WidgetName.html' | relative_url }}"
  width="100%" height="560" frameborder="0"
  style="border-radius: 12px; border: 1px solid #e2e8f0;"></iframe>

7. Rebuild Jekyll and test

bundle exec jekyll build                        # ~60 seconds
bundle exec jekyll serve --skip-initial-build --livereload

Common Pitfalls

Problem	Cause	Fix
Jekyll build hangs forever	HTML file has front matter → Liquid processes 350KB of minified JS	Remove front matter. File must start with <!DOCTYPE html>
Jekyll build takes 10+ minutes	node_modules exists inside blog repo assets	Keep build folder outside blog repo at C:\Users\kkanjitajdin\widget-builds\
Widget shows raw JSX text	Build didn't inline properly	Use vite-plugin-singlefile, verify dist/index.html contains <script> and <style> tags
iframe shows "refused to connect"	Wrong path — missing /mcscatblog/ baseurl	Use {{ '...' | relative_url }} in the iframe src
Widget doesn't render	shadcn imports not resolved	Create inline component file, rewrite imports

Rebuilding After Source Changes

Edit the .jsx in the blog repo, then:

cd C:\Users\kkanjitajdin\widget-builds\<widget-name>
Copy-Item "C:\Users\kkanjitajdin\mcscatblog\assets\posts\<post-slug>\WidgetName.jsx" "src\App.jsx" -Force
# Fix imports if needed (see step 4)
npm run build                                    # ~25 seconds
Copy-Item "dist\index.html" "C:\Users\kkanjitajdin\mcscatblog\assets\posts\<post-slug>\WidgetName.html" -Force
# Then rebuild Jekyll from the blog repo
cd C:\Users\kkanjitajdin\mcscatblog
bundle exec jekyll build                         # ~60 seconds
bundle exec jekyll serve --skip-initial-build --livereload

First-Time Setup for a New Widget

Only needed once per widget:

# Create build folder
New-Item -ItemType Directory -Force "C:\Users\kkanjitajdin\widget-builds\<widget-name>\src\components\ui"

# Copy/create: package.json, vite.config.js, index.html, src/main.jsx, src/index.css, src/components/ui/card.jsx
# (See sections 2-4 above for file contents)

# Install dependencies (one time)
cd C:\Users\kkanjitajdin\widget-builds\<widget-name>
npm install