DownZip

The package.json description says it all: "Library to enable client-side code to stream potentially large files into a zipped download"

Features

Client-side generation of ZIP files from supplied single-file download URLs
Support for ZIP64 (ZIP files bigger than 4GB)
Everything is streamed, no data has to be held in RAM
No compression is applied, so the CPU load is tiny

Installation

Install npm package: npm install downzip
Make sure the service worker is copied to your output directory. For example, setup copy-webpack-plugin to put the service worker in your output directory:

// Add copy rule for downzip service worker
new CopyPlugin([
    {
        from: 'node_modules/downzip/dist/downzip-sw.js',
        to: '.'
    }
])

Example usage

import DownZip from 'downzip'

// Setup downzip object
const downZip = new DownZip()
await downZip.register()

// Initialize download
const downloadId = "aaaabbbb"
const zipFileName = "downzip-file"
const files = [
    {
        name: 'picture1.jpg' 
        downloadUrl: 'http://your-download-url.com/picture1.jpg'
        size: 1234      // In bytes
    }, 
    {
        name: 'picture2.jpg' 
        downloadUrl: 'http://your-download-url.com/picture2.jpg'
        size: 4567      // In bytes
    }
]
const downloadUrl = await downZip.downzip(
    downloadId,
    zipFileName,
    files
)

// Start download when user clicks the link
<a href={downloadUrl}>Click to start downloading!</a>

service-worker-loader options

Can pass mapScriptUrl function to the register method. That function gets used by service-worker-loader. docs

    const mapScriptUrl = scriptUrl => scriptUrl.replace('localhost', "127.0.0.1")

   // Setup downzip object
    const downZip = new DownZip()
    await downZip.register({ mapScriptUrl })

TODO

All improvements are welcome, but the main things that need to be improved at the moment are:

Automated Testing
Only send the keep-alive service worker message when there is a download queued up / in progress
Find an easier way to install this package / service worker in projects