bun-build

Bun Production Build Configuration

Set up production builds using Bun's native bundler - fast, optimized bundle creation without webpack or esbuild.

Quick Reference

For detailed patterns, see:

• Build Targets: targets.md - Browser, Node.js, library, CLI configurations
• Optimization: optimization.md - Tree shaking, code splitting, analysis
• Plugins: plugins.md - Custom loaders and transformations

Core Workflow

1. Check Prerequisites

# Verify Bun installation
bun --version

# Check project structure
ls -la package.json src/

2. Determine Build Requirements

Ask the user about their build needs:

• Application Type: Frontend SPA, Node.js backend, CLI tool, or library
• Target Platform: Browser, Node.js, Bun runtime, or Cloudflare Workers
• Output Format: ESM (modern), CommonJS (legacy), or both

3. Create Basic Build Script

Create build.ts in project root:

#!/usr/bin/env bun

const result = await Bun.build({
  entrypoints: ['./src/index.ts'],
  outdir: './dist',
  target: 'browser', // or 'node', 'bun'
  format: 'esm', // or 'cjs', 'iife'
  minify: true,
  splitting: true,
  sourcemap: 'external',
});

if (!result.success) {
  console.error('Build failed');
  for (const message of result.logs) {
    console.error(message);
  }
  process.exit(1);
}

console.log('✅ Build successful');
console.log(`📦 ${result.outputs.length} files generated`);

// Show bundle sizes
for (const output of result.outputs) {
  const size = (output.size / 1024).toFixed(2);
  console.log(`  ${output.path} - ${size} KB`);
}

4. Configure for Target Platform

For Browser/Frontend:

await Bun.build({
  entrypoints: ['./src/index.tsx'],
  outdir: './dist',
  target: 'browser',
  format: 'esm',
  minify: true,
  splitting: true,
  define: {
    'process.env.NODE_ENV': '"production"',
  },
  loader: {
    '.png': 'file',
    '.svg': 'dataurl',
    '.css': 'css',
  },
});