batch.js

module.exports = Batch

function Batch(sync) {
  if(!(this instanceof Batch)) {
    return new Batch(sync)
  }

  this.jobs = []
  this.sync = sync
  this.frame = null
  this.run = this.run.bind(this)
}

Batch.prototype.request_frame = request_frame
Batch.prototype.queue = queue
Batch.prototype.add = add
Batch.prototype.run = run

function add(fn) {
  var queued = false
    , batch = this
    , self
    , args

  return queue

  function queue() {
    args = [].slice.call(arguments)
    self = this

    if(!queued) {
      queued = true
      batch.queue(run)
    }
  }

  function run() {
    queued = false
    fn.apply(self, args)
  }
}

function queue(fn) {
  this.jobs.push(fn)

  if(!this.sync) {
    this.request_frame()
  }
}

function run() {
  var jobs = this.jobs

  this.jobs = []
  this.frame = null

  for(var i = 0, l = jobs.length; i < l; ++i) {
    jobs[i]()
  }
}

function request_frame() {
  if(this.frame) {
    return
  }

  this.frame = requestAnimationFrame(this.run)
}

function requestAnimationFrame(callback) {
  var raf = global.requestAnimationFrame ||
    global.webkitRequestAnimationFrame ||
    global.mozRequestAnimationFrame ||
    timeout

  return raf(callback)

  function timeout(callback) {
    return setTimeout(callback, 1000 / 60)
  }
}