Node.js zlib.createGunzip() Method

Last Updated : 28 Apr, 2025

The zlib.createGunzip() method is an inbuilt application programming interface of the Zlib module which is used to create a new Gunzip object. 

Syntax:

zlib.createGunzip( options )

Parameters: This method accepts single parameter options which is an optional parameter that holds the zlib options. 

Return Value: It returns a new Gunzip object. 

The below examples illustrate the use of zlib.createGunzip() method in Node.js: 

Example 1: 

javascript 
// Node.js program to demonstrate the     
// createGunzip() method

// Including zlib module
const zlib = require('zlib');

// Calling gzip function to compress data
zlib.gzip('GeeksforGeeks', function (err, data) {
    if (err) {
        return console.log('err', err);
    }

    // Calling createGunzip method
    // to decompress the data again
    const gunzip = zlib.createGunzip();
    gunzip.write(data);
    gunzip.on('data', function (data) {
        console.log(data.toString());
    });
});

Output:

GeeksforGeeks

Example 2: 

javascript 
// Node.js program to demonstrate the     
// createGunzip() method

// Including zlib module
const zlib = require('zlib');

// Calling gzip function to compress data
zlib.gzip('GfG', function (err, data) {
    if (err) {
        return console.log('err', err);
    }

    // Calling createGunzip method
    // to decompress the data again
    const gunzip = zlib.createGunzip();
    gunzip.write(data);
    gunzip.on('data', function (data) {
        // Encoding the data
        console.log(data.toString('hex'));
    });
});

Output:

476647

Reference: https://nodejs.org/api/zlib.html#zlib_zlib_creategunzip_options

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