csev/importmap

Playground for some example importmap code

Web Components Demo

A simple demonstration using ES modules with import maps for development and esbuild for production builds.

Project Structure

• index.html - Main HTML file with import map configuration
• main.js - JavaScript module with date formatting functionality
• tools/generate_importmap.php - PHP tool to sync import map from package.json
• tools/build.js - esbuild production build script

Development

This project can be run directly in the browser using import maps. No build step is required for development.

Running in Development

Using PHP (automatically generates import map):

php -S localhost:8000

Or using Python (with static import map):

python -m http.server 8000

Then visit http://localhost:8000 in your browser.

Production Build

For production, we use esbuild to create optimized builds. This will:

• Bundle all dependencies
• Tree-shake unused code
• Create optimized assets
• Remove the need for import maps

Building for Production

1. Install dependencies:

npm install

2. Create production build:

npm run build

3. Serve the production build:

cd dist
python -m http.server 8000

Then visit http://localhost:8000 to see the optimized production version.

Dependencies

Development (via import maps):

• Day.js v1.10.7 (from Skypack CDN)

Production (handled by esbuild):

• Dependencies are bundled from npm packages
• No runtime CDN dependencies
• Optimized and minified output

Browser Support

• Development: Browsers with import map support (all modern browsers)
• Production: All modern browsers (IE11 not supported)

Notes

• Development uses import maps for direct in-browser module loading
• Production builds use esbuild for optimization
• PHP development server provides automatic import map generation
• Tree-shaking ensures minimal bundle size