strum

Make a stream out of almost anything

Example

var strum = require('strum')

strum([1, 2, 3]).pipe(process.stdout)
strum(new Set([4, 5, 6])).pipe(strum(times2)).pipe(process.stdout)

function times2 (x) {
  return x * 2
}

Kinda handy, but where things get really neat:

var strum = require('strum')
var fetch = require('isomorphic-fetch')

strum(['dogs', 'cats', 'bears', 'gorillas'])
  .pipe(strum(makeRequest))
  .pipe(process.stdout)

function makeRequest (query) {
  return fetch('/some/api/?query=' + query)
    .then(function (response) {
      return response.text()
    })
}

It understands promises! any data source that returns a promise will be handled smartly, such that: if it resolves, the resolved value is emitted (rather than the promise itself), and if it is rejected, an error event is emitted with the rejected value.

Here, have another contrived (but more ES6y!) example:

const strum = require('strum')

strum(foreverRandom())
  .pipe(strum(headsOrTails))
  .pipe(process.stdout)

function headsOrTails (num) {
  return (num < 0.5 ? 'heads' : 'tails') + '\n'
}

function * foreverRandom () {
  while (true) {
    yield new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve(Math.random())
      }, 1000)
    })
  }
}

API

strum(source, _streamOptions) -> stream

• source can be any of:

  • A stream: yields the exact same stream.
  • An array: yields a readable stream, emitting once for each item.
  • An iterable: yields a readable stream, emitting once for every .next().
  • A promise: yields a readable stream that emits once the promise is realized.
  • A function: yields a transform stream, which is called with the value of each write, and will emit with each returned value.

• _streamOptions is an optional object that will be passed to the stream constructor.

Notes

• The returned value is by default a standard node stream in objectMode. This can be overridden by passing {objectMode: false} as your options object.
• Contributions welcome!

License

MIT