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Express Middleware Example

Demonstrates using Express middleware with Vegaa's minimal API.

Code​

import { vegaa, route, enableExpressCompat, html } from 'vegaa'

async function main() {
  // Enable Express compatibility
  enableExpressCompat(vegaa)
  console.log('✅ Express compatibility enabled')

  // Example 1: Simple Express middleware (logging)
  vegaa.useExpressMiddleware((req, res, next) => {
    console.log(`📝 [Express MW] ${req.method} ${req.url}`)
    req.requestTime = new Date().toISOString()
    next()
  })

  // Example 2: Express middleware with path prefix
  vegaa.useExpressMiddleware('/api', (req, res, next) => {
    req.apiVersion = 'v1'
    console.log(`🔌 [API Middleware] API Version: ${req.apiVersion}`)
    next()
  })

  // Example 3: Express middleware that modifies response
  vegaa.useExpressMiddleware((req, res, next) => {
    res.setHeader('X-Powered-By', 'Vegaa')
    next()
  })

  // Example 4: Async Express middleware
  vegaa.useExpressMiddleware(async (req, res, next) => {
    await new Promise(resolve => setTimeout(resolve, 10))
    req.asyncData = { loaded: true, timestamp: Date.now() }
    next()
  })

  // Vegaa routes - Express middleware properties available via context
  route('/').get((requestTime, asyncData) => {
    return html(`
      <!DOCTYPE html>
      <html>
        <head><title>Express Middleware Demo</title></head>
        <body>
          <h1>Express Middleware Integration</h1>
          <p>Request Time: ${requestTime}</p>
          <p>Async Data: ${JSON.stringify(asyncData)}</p>
        </body>
      </html>
    `)
  })

  route('/api/users').get((apiVersion) => {
    return {
      version: apiVersion,
      users: [{ id: 1, name: 'John' }]
    }
  })

  // Start server
  await vegaa.startVegaaServer({ port: 4000 })
  console.log('✅ Server running on http://localhost:4000')
}

main().catch(err => {
  console.error('💥 Server failed:', err)
  process.exit(1)
})

Try It​

Using Real Express Middleware​

If you have Express packages installed, you can use them:

import helmet from 'helmet'
import cors from 'cors'

enableExpressCompat(vegaa)
vegaa.useExpressMiddleware(helmet())
vegaa.useExpressMiddleware(cors())

Key Concepts​

  • Express Compatibility - Use existing Express middleware
  • Context Integration - Express req properties become available in Vegaa routes
  • Path-Specific - Apply middleware to specific paths
  • Clean API - Keep Vegaa's minimal API while using Express middleware

Next Steps​