Convert a stream to a Buffer in Node.js

BufferStream.js

import { Writable } from 'stream'

/**
 * Create a Buffer from a stream (warning: loads all chunks into memory)
 * Usage: myStream.pipe(new BufferStream(buffer => {}, err => {}))
 */
export default class BufferStream extends Writable {

  data = []

  constructor(onComplete, onError) {
    super()

    this.on('finish', () => onComplete(Buffer.concat(this.data)))
    this.on('error', onError)
  }

  _write(chunk, encoding, next) {
    this.data.push(chunk)
    next()
  }
}