Remove root directory from zip file

rezip.ts

import { readFile, writeFile } from 'fs'
import { promisify } from 'util'
import * as JSZip from 'jszip'

const main = async () => {
  const oldPath = 'old.zip'
  const oldBuf = await promisify(readFile)(oldPath)
  const oldZip = await JSZip.loadAsync(oldBuf)
  const files = oldZip.files

  const newZip = new JSZip()
  const promises = Object.keys(files)
    .filter(key => !files[key].dir)
    .map(async key => {
      const file = files[key]
      const buffer = await file.async('nodebuffer')
      const path = file.name
        .split('/')
        .slice(1)
        .join('/')
      newZip.file(path, buffer)
    })
  await Promise.all(promises)
  const newBuf = await newZip.generateAsync({ type: 'nodebuffer' })
  const newPath = 'new.zip'
  await promisify(writeFile)(newPath, newBuf)
}

main()
  .then(console.log)
  .catch(console.error)