google/zx 8.2.3

8.2.3 – Golden Wrench

on GitHub

const { stdout } = await $({ halt: true })`echo "hello"`
 .pipe`awk '{print $1" world"}'`
 .pipe`tr '[a-z]' '[A-Z]'`
 .run()

stdout // 'HELLO WORLD'

const getUpperCaseTransform = () =>
  new Transform({
    transform(chunk, encoding, callback) {
      callback(null, String(chunk).toUpperCase())
    },
  })

// $ > stream (promisified) > $ 
const o1 = await $`echo "hello"`
  .pipe(getUpperCaseTransform())
  .pipe($`cat`)

o1.stdout //  'HELLO\n'

// stream > $
const file = tempfile()
await fs.writeFile(file, 'test')
const o2 = await fs
  .createReadStream(file)
  .pipe(getUpperCaseTransform())
  .pipe($`cat`)

o2.stdout //  'TEST'

const file = tempfile()
const fileStream = fs.createWriteStream(file)
const p = $`echo "hello"`
  .pipe(getUpperCaseTransform())
  .pipe(fileStream)
const o = await p

p instanceof WriteStream             // true
o instanceof WriteStream             // true
o.stdout                             // 'hello\n'
o.exitCode;                          // 0
(await fs.readFile(file)).toString() // 'HELLO\n'