# JSZip — Create and Read ZIP Files in JavaScript

> A JavaScript library for creating, reading, and editing ZIP archives in the browser and Node.js with an intuitive promise-based API.

## Install

Save in your project root:

# JSZip — Create and Read ZIP Files in JavaScript

## Quick Use
```bash
npm install jszip
```
```js
import JSZip from 'jszip';

const zip = new JSZip();
zip.file('hello.txt', 'Hello World');
zip.folder('data').file('info.json', JSON.stringify({ version: 1 }));

const blob = await zip.generateAsync({ type: 'blob' });
// Use the blob for download or upload
```

## Introduction
JSZip lets developers create, read, and modify ZIP archives entirely in JavaScript. It runs in the browser without server-side processing, enabling features like client-side file bundling, in-memory archive inspection, and offline export of multi-file downloads—all with a clean promise-based API.

## What JSZip Does
- Creates ZIP archives from strings, blobs, array buffers, and typed arrays
- Reads and extracts contents from existing ZIP files
- Supports nested folder structures within archives
- Generates output as Blob, ArrayBuffer, Uint8Array, base64, or Node.js Buffer
- Handles DEFLATE compression with configurable compression level

## Architecture Overview
JSZip maintains an in-memory tree of entries representing files and folders. Each entry stores its content and metadata (name, date, compression method). When reading a ZIP, the library parses the central directory and local file headers per the PKZIP specification, inflating compressed entries on demand. When generating, it serializes the entry tree into a valid ZIP byte stream, compressing entries with the pako DEFLATE library. All operations return promises, allowing non-blocking processing of large archives.

## Setup & Configuration
- Install via npm or load from a CDN for browser use
- Create a new archive with `new JSZip()` and add files with `.file(name, content)`
- Read an existing ZIP with `JSZip.loadAsync(data)` where data is a Blob, ArrayBuffer, or base64 string
- Set compression options in `generateAsync()`: `{ compression: 'DEFLATE', compressionOptions: { level: 6 } }`
- Access individual files with `zip.file('path/to/file').async('string')` for lazy extraction

## Key Features
- Pure JavaScript with no native dependencies or WebAssembly
- Reads and writes ZIP64 archives for files larger than 4 GB
- Streaming generation via `generateInternalStream()` for memory-efficient output
- Compatible with password-protected ZIP reading via community extensions
- Works identically in browser, Node.js, and Deno environments

## Comparison with Similar Tools
- **Archiver (Node.js)** — streaming ZIP creation for servers; JSZip also works in the browser
- **fflate** — faster compression via WebAssembly; JSZip has a simpler API and wider adoption
- **pako** — raw DEFLATE compression only; JSZip provides the full ZIP container format on top
- **StreamSaver.js** — handles downloading large files; pair with JSZip to stream ZIP downloads in the browser

## FAQ
**Q: Can JSZip handle large archives in the browser?**
A: Yes. Use `generateInternalStream()` for streaming output and `loadAsync()` for lazy parsing. Very large archives may still be constrained by browser memory limits.

**Q: Does JSZip support password-protected ZIP files?**
A: The core library does not encrypt or decrypt. Community forks and plugins add password support using the traditional ZIP encryption scheme.

**Q: Can I add binary files like images to a ZIP?**
A: Yes. Pass the content as a Blob, ArrayBuffer, or Uint8Array to `zip.file()` and set `{ binary: true }` if needed.

**Q: How does JSZip compare to the native Compression Streams API?**
A: The Compression Streams API provides raw DEFLATE/gzip compression. JSZip adds the ZIP container format, file metadata, and folder structure on top of compression.

## Sources
- https://github.com/Stuk/jszip
- https://stuk.github.io/jszip/

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Source: https://tokrepo.com/en/workflows/asset-fe23e40c
Author: AI Open Source