Express.js-Komprimierungs-Middleware-Generator

npm install compression

const compression = require('compression');
const express = require('express');

// Custom filter - skip compression for already-compressed content types
function shouldCompress(req, res) {
  // Don't compress responses with this request header
  if (req.headers['x-no-compression']) return false;

  // Skip already-compressed content types
  const contentType = res.getHeader('Content-Type');
  if (typeof contentType === 'string') {
    const skipTypes = [
      'image/jpeg', 'image/png', 'image/webp', 'image/avif',
      'image/gif', 'video/', 'audio/', 'application/zip',
      'application/gzip', 'application/x-bzip2', 'font/woff2',
    ];
    if (skipTypes.some(t => contentType.startsWith(t))) return false;
  }

  // Fall back to default compression filter
  return compression.filter(req, res);
}

const app = express();

// -- Compression middleware ----------------------------------------------------
// Must be registered BEFORE routes and static file serving
app.use(compression({
  // Compression level: 1 (fastest) to 9 (smallest). Default is zlib.Z_DEFAULT_COMPRESSION (6).
  level: 6,

  // Only compress responses above this byte threshold
  threshold: 1024, // 1KB

  // Custom filter function - skips already-compressed content types
  filter: shouldCompress,
}));

// Ensure Vary: Accept-Encoding is set for correct CDN caching
app.use((_req, res, next) => {
  res.setHeader('Vary', 'Accept-Encoding');
  next();
});

// -- Your routes --------------------------------------------------------------
app.get('/', (req, res) => {
  res.json({ message: 'Hello, compressed world!' });
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

// -- Brotli support note ------------------------------------------------------
// The 'compression' package only supports GZIP and DEFLATE.
// For Brotli support in Express, use 'shrink-ray-current' instead:
//
//   npm install shrink-ray-current
//
//   const shrinkRay = require('shrink-ray-current');
//   app.use(shrinkRay());
//
// Or use 'express-static-gzip' to serve pre-compressed .br and .gz files:
//   npm install express-static-gzip