Streams using async generators

index.mjs

import { pipeline } from 'stream/promises'

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms))

const colorsGenerator = async function* () {
  const values = [ 'yellow', 'orange', 'red', 'blue', 'purple', 'green' ]

  for await (const color of values) {
    yield color
    await sleep(1000)
  }
}

const wordUpperCaser = async function* (source) {
  for await (const chunk of source) {
    yield chunk.toUpperCase()
  }
}

const letterUnderscorer = async function* (source) {
  for await (const chunk of source) {
    yield chunk.split('').join('_')
  }
}

const chunkLogger = async function (source) {
  for await (const chunk of source) {
    console.log(chunk)
  }
}

await pipeline(colorsGenerator, wordUpperCaser, letterUnderscorer, chunkLogger)