Introduction

zip.js is a JavaScript open-source library (BSD-3-Clause license) for compressing and decompressing zip files. It has been designed to handle large amounts of data. It supports notably multi-core compression, native compression with compression streams, pluggable compression engines, archives larger than 4GB with Zip64, split zip files, data encryption, incremental writing, and Deflate64 decompression.

Demo

See https://gildas-lormeau.github.io/zip-manager

Documentation

See here for more info: https://gildas-lormeau.github.io/zip.js/

Examples

Hello world

import {
  BlobReader,
  BlobWriter,
  TextReader,
  TextWriter,
  ZipReader,
  ZipWriter
} from "@zip.js/zip.js";
// "jsr:@zip-js/zip-js" for Deno

// ----
// Write the zip file
// ----

// Creates a BlobWriter object where the zip content will be written.
const zipFileWriter = new BlobWriter();
// Creates a TextReader object storing the text of the entry to add in the zip
// (i.e. "Hello world!").
const helloWorldReader = new TextReader("Hello world!");

// Creates a ZipWriter object writing data via `zipFileWriter`, adds the entry
// "hello.txt" containing the text "Hello world!" via `helloWorldReader`, and
// closes the writer.
const zipWriter = new ZipWriter(zipFileWriter);
await zipWriter.add("hello.txt", helloWorldReader);
await zipWriter.close();

// Retrieves the Blob object containing the zip content into `zipFileBlob`. It
// is also returned by zipWriter.close() for more convenience.
const zipFileBlob = await zipFileWriter.getData();

// ----
// Read the zip file
// ----

// Creates a BlobReader object used to read `zipFileBlob`.
const zipFileReader = new BlobReader(zipFileBlob);
// Creates a TextWriter object where the content of the first entry in the zip
// will be written.
const helloWorldWriter = new TextWriter();

// Creates a ZipReader object reading the zip content via `zipFileReader`,
// retrieves metadata (name, dates, etc.) of the first entry, retrieves its
// content via `helloWorldWriter`, and closes the reader.
const zipReader = new ZipReader(zipFileReader);
const firstEntry = (await zipReader.getEntries()).shift();
const helloWorldText = await firstEntry.getData(helloWorldWriter);
await zipReader.close();

// Displays "Hello world!".
console.log(helloWorldText);

Run the code on JSFiddle: https://jsfiddle.net/tm9fhvab/

Hello world with the filesystem API

The filesystem API stores the entries in a tree instead of a flat list. It needs a single import, it infers the Reader and the Writer from the type of the data, and it reaches an entry from its name instead of searching it in an array.

import { ZipFS } from "@zip.js/zip.js";
// "jsr:@zip-js/zip-js" for Deno

// ----
// Write the zip file
// ----

// Creates a ZipFS object and adds two entries to it. The name of an entry is a
// path, so the "folder" directory is created by the second call.
const zipFs = new ZipFS();
zipFs.addText("hello.txt", "Hello world!");
zipFs.addText("folder/hello.txt", "Hello world from a directory!");

// Retrieves the Blob object containing the zip content.
const zipFileBlob = await zipFs.exportBlob();

// ----
// Read the zip file
// ----

// Imports the zip content into a new ZipFS object, then retrieves the content
// of the entries from their full name.
const importedZipFs = new ZipFS();
await importedZipFs.importBlob(zipFileBlob);
const helloWorldText = await importedZipFs.find("hello.txt").getText();
const nestedText = await importedZipFs.find("folder/hello.txt").getText();

// Displays "Hello world!" and "Hello world from a directory!".
console.log(helloWorldText, nestedText);

Run the code on JSFiddle: https://jsfiddle.net/gcnret0x/

Hello world with Streams

import {
  BlobReader,
  ZipReader,
  ZipWriter
} from "@zip-js/zip-js";
// Prefix "@zip-js/zip-js" with "jsr:" for Deno

// ----
// Write the zip file
// ----

// Creates a TransformStream object, the zip content will be written in the
// `writable` property.
const zipFileStream = new TransformStream();
// Creates a Promise object resolved to the zip content returned as a Blob
// object retrieved from `zipFileStream.readable`.
const zipFileBlobPromise = new Response(zipFileStream.readable).blob();
// Creates a ReadableStream object storing the text of the entry to add in the
// zip (i.e. "Hello world!").
const helloWorldReadable = new Blob(["Hello world!"]).stream();

// Creates a ZipWriter object writing data into `zipFileStream.writable`, adds
// the entry "hello.txt" containing the text "Hello world!" retrieved from
// `helloWorldReadable`, and closes the writer.
const zipWriter = new ZipWriter(zipFileStream.writable);
await zipWriter.add("hello.txt", helloWorldReadable);
await zipWriter.close();

// Retrieves the Blob object containing the zip content into `zipFileBlob`.
const zipFileBlob = await zipFileBlobPromise;

// ----
// Read the zip file
// ----

// Creates a BlobReader object used to read `zipFileBlob`.
const zipFileReader = new BlobReader(zipFileBlob);
// Creates a TransformStream object, the content of the first entry in the zip
// will be written in the `writable` property.
const helloWorldStream = new TransformStream();
// Creates a Promise object resolved to the content of the first entry returned
// as text from `helloWorldStream.readable`.
const helloWorldTextPromise = new Response(helloWorldStream.readable).text();

// Creates a ZipReader object reading the zip content via `zipFileReader`,
// retrieves metadata (name, dates, etc.) of the first entry, retrieves its
// content into `helloWorldStream.writable`, and closes the reader.
const zipReader = new ZipReader(zipFileReader);
const firstEntry = (await zipReader.getEntries()).shift();
await firstEntry.getData(helloWorldStream.writable);
await zipReader.close();

// Displays "Hello world!".
const helloWorldText = await helloWorldTextPromise;
console.log(helloWorldText);

Run the code on JSFiddle: https://jsfiddle.net/aw3d6f4o/

Adding concurrently multiple entries in a zip file

import {
  BlobWriter,
  HttpReader,
  TextReader,
  ZipWriter,
} from "@zip-js/zip-js";
// Prefix "@zip-js/zip-js" with "jsr:" for Deno

const README_URL = "https://unpkg.com/@zip.js/zip.js/README.md";
getZipFileBlob()
  .then(downloadFile);

async function getZipFileBlob() {
  const zipWriter = new ZipWriter(new BlobWriter("application/zip"));
  await Promise.all([
    zipWriter.add("hello.txt", new TextReader("Hello world!")),
    zipWriter.add("README.md", new HttpReader(README_URL)),
  ]);
  return zipWriter.close();
}

function downloadFile(blob) {
  document.body.appendChild(Object.assign(document.createElement("a"), {
    download: "hello.zip",
    href: URL.createObjectURL(blob),
    textContent: "Download zip file",
  }));
}

Run the code on Plunker: https://plnkr.co/edit/4sVljNIpqSUE9HCA?preview

Custom web workers and compression engines

zip.js lets you create its web workers yourself by using the new Worker(new URL("./zip-worker.js", import.meta.url)) form. Bundlers like Vite, webpack and Rollup detect it and bundle the worker automatically. You can also delegate compression and decompression to a custom engine, e.g. fflate:

import { configure } from "@zip.js/zip.js/lib/zip-core-custom.js";

configure({
  createWorker: () => new Worker(
    new URL("./zip-worker.js", import.meta.url),
    { type: "module" }
  )
});

// zip-worker.js
import { initWorker } from "@zip.js/zip.js/worker";
import { CompressionStreamFallback, DecompressionStreamFallback } from "./fflate-streams.js";

initWorker({ CompressionStreamFallback, DecompressionStreamFallback });

See https://gildas-lormeau.github.io/zip.js/#custom-workers for a complete guide.

Tests

See https://github.com/gildas-lormeau/zip.js/tree/master/tests/all