Namespace "zlib"

The zlib module provides compression functionality implemented using Gzip, Deflate/Inflate, and Brotli.

To access it:

const zlib = require('zlib');

Compression and decompression are built around the Node.js Streams API.

Compressing or decompressing a stream (such as a file) can be accomplished by piping the source stream through a zlib Transform stream into a destination stream:

const { createGzip } = require('zlib');
const { pipeline } = require('stream');
const {
createReadStream,
createWriteStream
} = require('fs');

const gzip = createGzip();
const source = createReadStream('input.txt');
const destination = createWriteStream('input.txt.gz');

pipeline(source, gzip, destination, (err) => {
if (err) {
console.error('An error occurred:', err);
process.exitCode = 1;
}
});

// Or, Promisified

const { promisify } = require('util');
const pipe = promisify(pipeline);

async function do_gzip(input, output) {
const gzip = createGzip();
const source = createReadStream(input);
const destination = createWriteStream(output);
await pipe(source, gzip, destination);
}

do_gzip('input.txt', 'input.txt.gz')
.catch((err) => {
console.error('An error occurred:', err);
process.exitCode = 1;
});

It is also possible to compress or decompress data in a single step:

const { deflate, unzip } = require('zlib');

const input = '.................................';
deflate(input, (err, buffer) => {
if (err) {
console.error('An error occurred:', err);
process.exitCode = 1;
}
console.log(buffer.toString('base64'));
});

const buffer = Buffer.from('eJzT0yMAAGTvBe8=', 'base64');
unzip(buffer, (err, buffer) => {
if (err) {
console.error('An error occurred:', err);
process.exitCode = 1;
}
console.log(buffer.toString());
});

// Or, Promisified

const { promisify } = require('util');
const do_unzip = promisify(unzip);

do_unzip(buffer)
.then((buf) => console.log(buf.toString()))
.catch((err) => {
console.error('An error occurred:', err);
process.exitCode = 1;
});

See

source

Index

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