How to use gzip in nodejs server

When sending HTTP responses in a Node.js server, you typically need to manually configure compression to ensure that the data is compressed before being sent to the client. The HTTP response object in Node.js does not automatically compress the data; you need to use middleware or manually apply compression techniques.

Using Middleware for Automatic Compression

In a typical Node.js application using Express, you can use the compression middleware to automatically compress HTTP responses. This middleware uses zlib under the hood to handle compression and makes it easy to add gzip compression to your responses without manually compressing the data yourself.

Example: Enabling Gzip Compression with Express and Compression Middleware

1. Install the compression middleware:

npm install compression

2. Use the compression middleware in your Express application:

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

const app = express();

// Enable gzip compression
app.use(compression());

app.get('/', (req, res) => {
  const data = 'Hello, this is a response from the server!';
  res.send(data);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

With this setup, the compression middleware automatically compresses the response if the client supports gzip compression (as indicated by the Accept-Encoding header).

Manually Compressing HTTP Responses

If you are not using a framework like Express or if you need more control over the compression process, you can manually compress the response data using the zlib module.

Example: Manually Compressing an HTTP Response

const http = require('http');
const zlib = require('zlib');

const server = http.createServer((req, res) => {
  const data = 'Hello, this is a response from the server!';

  // Check if the client supports gzip compression
  const acceptEncoding = req.headers['accept-encoding'];
  if (acceptEncoding && acceptEncoding.includes('gzip')) {
    // Compress the response using gzip
    zlib.gzip(data, (err, buffer) => {
      if (err) {
        res.writeHead(500, { 'Content-Type': 'text/plain' });
        res.end('Internal Server Error');
      } else {
        res.writeHead(200, {
          'Content-Type': 'text/plain',
          'Content-Encoding': 'gzip',
        });
        res.end(buffer);
      }
    });
  } else {
    // Send uncompressed response
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end(data);
  }
});

server.listen(3000, () => {
  console.log('Server is running on port 3000');
});

In this example, the server checks if the client supports gzip compression by inspecting the Accept-Encoding header. If gzip is supported, the response is compressed using zlib.gzip before being sent to the client. If gzip is not supported, the server sends the uncompressed response.