Node.JS script to losslessly convert an iOS .imageset to an Android mipmap

imageset2mipmap.js

#!/usr/bin/env node
const FS = require('fs')
const Path = require('path')

const FolderMap = {
    "1x": "mipmap-mdpi",
    "2x": "mipmap-xhdpi",
    "3x": "mipmap-xxhdpi",
}

const srcfolder = process.argv[2]
if (srcfolder === undefined) {
    console.log(`Usage: ${process.argv[1]} IMAGESET [RES_FOLDER]`)
    process.exit(2)
}

const destfolder = process.argv[3]
const json = JSON.parse(FS.readFileSync(Path.join(srcfolder, 'Contents.json')))
json.images.forEach(img => {

    const destname = Path.basename(srcfolder, ".imageset") + Path.extname(img.filename)
    const dest = Path.join(destfolder ? destfolder : ".", FolderMap[img.scale], destname)
    const src = Path.join(srcfolder, img.filename)
    console.log(src, '->', dest)
    FS.createReadStream(src).pipe(FS.createWriteStream(dest))
})