common-streams

A collection of useful streams.

Install

npm install --save common-streams

Requires Node v6+

Usage

See ./test directory for more usage examples.

Example:

import { HashStream, SizeStream } from 'common-streams'
import concat from 'concat-stream'

const rs = getReadStream() // e.g. fs.createReadStream(...)
const ws = getWriteStream() // e.g. fs.createWriteStream(...)

const sha1Stream = new HashStream('sha1')
const sizeStream = new SizeStream()

rs.pipe(sha1Stream).pipe(concat(([{ digest }]) => {
  console.log(digest, '=', '4129def2ea7cb7945ddfbb785969898fca2e34c3')
}))
rs.pipe(sizeStream).pipe(concat(([{ size }]) => {
  console.log(size, '=', 2447774)
}))
rs.pipe(ws)

HashStream

Transform stream that operates in object mode and returns a single { digest: 'hash digest' } object.

new HashStream(algorithm, [, opts])

algorithm: any algorithm supported by crypto.createHash

opts.encoding: any encoding supported by hash.digest. Defaults to hex.

SizeStream

Transform stream that operates in object mode and returns a single { size: 1000 } object where the size is an integer representing the total size in bytes of the stream.

new SizeStream()

If passed a callback new SizeStream(cb) it will just act as a PassThrough stream and call the callback when it's done.

RandomStream

new RandomStream(max)

Readable stream that emits max random bytes before ending.

DiscardStream

new DiscardStream(start)

Swallows all bytes until start is reached.

MeterStream

new MeterStream(max)

See meterstream