Concatenate two (or n) streams

Question

• 2 streams:

  Given readable streams stream1 and stream2, what\'s an idiomatic (concise) way to get a stream containing

Answer 1

This can now be easily done using async iterators

async function* concatStreams(readables) {
  for (const readable of readables) {
    for await (const chunk of readable) { yield chunk }
  }
} 

And you can use it like this

const fs = require('fs')
const stream = require('stream')

const files = ['file1.txt', 'file2.txt', 'file3.txt'] 
const iterable = await concatStreams(files.map(f => fs.createReadStream(f)))

// convert the async iterable to a readable stream
const mergedStream = stream.Readable.from(iterable)

More info regarding async iterators: https://2ality.com/2019/11/nodejs-streams-async-iteration.html