continue-stream

continue-stream

Lazily merge multiple streams in to a single stream. continueStream can also be thought of as a pagination stream.

npm install continue-stream

Usage

Pass continueStream a function that provides a new stream to it's callback. This function will be called on initialization and after each stream has ended. If the callback is called without any arguments the continueStream will end.

var continueStream = require('continue-stream')
var request = require('request')

var page = 1

function next(callback, previousStream) {
  if (page >= 4) return callback()

  var stream = request({
    url: 'https://api.github.com/repos/joyent/node/events?page=' + (page++),
    headers: {'user-agent': 'pug'}
  })

  callback(null, stream)
}

continueStream(next)
  .pipe(process.stdout)

Or you can use continueStream.obj as a convenience for objectMode

var continueStream = require('continue-stream')
var request = require('request')
var pumpify = require('pumpify')
var JSONStream = require('JSONStream')

var page = 1

function next(callback, previousStream) {
  if (page >= 4) return callback()

  var req = request({
    url: 'https://api.github.com/repos/joyent/node/events?page=' + (page++),
    headers: {'user-agent': 'pug'}
  })

  var stream = pumpify.obj(req, JSONStream.parse('*'))

  callback(null, stream)
}

continueStream.obj(next)
  .on('data', function(data) {
    console.log(data)
  })

A good use case for this is paginated requests. Need to read the last n pages of a feed and want all items piped through a single stream? That is exactly what the last example is showing.

License

MIT