Zlib Module in Node.js

The zlib module in Node.js is used to compress and decompress data using algorithms like Gzip and Deflate. It helps reduce data size, improving performance and saving bandwidth.

• Supports compression and decompression of data streams and buffers.
• Uses Gzip, Deflate, and Inflate algorithms for efficient data compression.
• Built on the zlib C library, providing reliable and high-performance compression.

Example: Compress a file (demofile.txt) into a gzip file (mygzipfile.txt.gz).

var fs = require('fs');
var zlib = require('zlib');

var x = fs.createReadStream('demofile.txt');
var y = fs.createWriteStream('mygzipfile.txt.gz');
var gzip = zlib.createGzip();
x.pipe(gzip).pipe(y);

Importing Module

To use the zlib module in your Node.js application, simply import it as below:

const zlib = require('zlib');

Features

The zlib module provides multiple functionalities for efficient data compression and decompression in Node.js applications.

• Compression and Decompression: Provides APIs to compress and decompress data using Gzip and Deflate algorithms.
• Stream Handling: Supports efficient compression and decompression of data streams.
• Buffer Operations: Allows compression and decompression of buffer data.
• Custom Compression Levels: Enables configuration of compression levels for speed or efficiency.

Zlib Methods

The zlib module provides several methods for compression and decompression.

• zlib.gzip():zlib.gzip() method compresses data using the Gzip compression algorithm.
• zlib.gunzip():zlib.gunzip() method decompresses Gzip-compressed data.
• zlib.deflate(): zlib.deflate() method compresses data using the Deflate algorithm.
• zlib.inflate(): zlib.inflate() method decompresses Deflate-compressed data.
• zlib.deflateRaw(): zlib.deflateRaw() method compresses data using the Deflate algorithm without headers or checksums.
• zlib.inflateRaw(): zlib.inflateRaw() method decompresses data that was compressed using deflateRaw().
• zlib.brotliCompress(): zlib.brotliCompress() method compresses data using the Brotli compression algorithm.
• zlib.brotliDecompress(): zlib.brotliDecompress() method decompresses Brotli-compressed data.

Example 1: Compressing a String

const zlib = require('zlib');

const s_in = 'This is a sample string to compress.';

zlib.gzip(s_in, (err, compressedBuffer) => {
    if (err) {
        console.error('Compression error:', err);
    } else {
        console.log('Compressed Buffer:', compressedBuffer);
        console.log('Compressed Buffer (Hex):', compressedBuffer.toString('hex'));
    }
});

Output:

Example 2: Decompressing a Gzip Buffer

console.clear();
const zlib = require("zlib");

const compressedBuffer = Buffer.from("your_hex_string_here", "hex");
zlib.gunzip(compressedBuffer, (err, buffer) => {
    if (err) {
        console.error("Error decompressing:", err);
    } else {
        console.log("Decompressed String:", buffer.toString());
    }
});

Output:

Benefits of Zlib Module

The zlib module improves data compression efficiency and performance in Node.js applications.

• Efficient Data Compression: Reduces data size to optimize storage and bandwidth usage.
• Built-In Support: Available as a core Node.js module without external dependencies.
• Flexible Compression: Supports multiple algorithms and customizable compression levels.
• Stream and Buffer Handling: Can process both data streams and buffers efficiently.

Also Check

• Zlib Module Complete Reference