Correctly Configuring publicPath for React Applications

When serving React apps, an incorrect publicPath can cause broken assets, failed loading, and routing issues. Here’s how to properly configure it for different deployment scenarios.

Understanding publicPath

publicPath determines:

Where your assets are served from
How files are referenced in your built HTML/CSS
The base URL for all your application’s assets

Common Symptoms of Incorrect publicPath

Blank white screen in production
404 errors for JavaScript/CSS files
Broken images and static assets
Failed API requests
Routing malfunctions

Configuration Solutions

1. Webpack Configuration (for custom setups)

// webpack.config.js
module.exports = {
  output: {
    publicPath: '/', // Default for root domain
    publicPath: '/my-app/', // For subdirectory
    publicPath: 'https://cdn.example.com/', // For CDN
  }
}

2. Create React App Solutions

Option A: package.json homepage field

{
  "homepage": "https://example.com/subdirectory"
}

Option B: Environment variables

# .env
PUBLIC_URL=/subdirectory

3. For Different Environments

Development:

publicPath: '/'

Production:

publicPath: process.env.PUBLIC_URL || '/'

Testing:

publicPath: './' // Relative paths

Deployment-Specific Configurations

GitHub Pages

{
  "homepage": "https://username.github.io/repo-name",
  "scripts": {
    "predeploy": "npm run build",
    "deploy": "gh-pages -d build"
  }
}

Netlify/Vercel

// No special config needed for root deployments
// For preview deployments:
publicPath: process.env.PUBLIC_URL || '/'

AWS S3/CloudFront

publicPath: process.env.CDN_URL || '/'

Dynamic Path Resolution

For advanced scenarios:

// webpack.config.js
const publicPath = process.env.NODE_ENV === 'production'
  ? 'https://cdn.example.com/'
  : '/';

module.exports = {
  output: { publicPath }
}

Troubleshooting Techniques

Inspect built index.html:

Check if asset paths match your deployment structure

Verify environment variables:

   echo $PUBLIC_URL

Test locally:

   serve -s build --listen 5000

Check network tab:

Look for failed resource loading

Best Practices

Set publicPath early in project setup
Use environment variables for flexibility
Test in staging before production
Document your deployment requirements
Consider using relative paths for more portable builds

Common Fixes for Specific Issues

Problem: Assets loading from wrong path
Solution:

publicPath: process.env.PUBLIC_URL || '/'

Problem: Routing breaks on refresh
Solution:

// webpack.config.js
publicPath: '/'
// plus proper server configuration to serve index.html for all routes

Problem: CDN assets not loading
Solution:

publicPath: 'https://your-cdn-url.com/'

Serving React app with incorrect publicPath