fibers.js

require('fibers')

function sleep(ms) {
  var fiber = Fiber.current;
  setTimeout(function() {
    fiber.run()
  }, ms)
  yield()
}

var x
Fiber(function() {
  x = 5
  sleep(0)
  console.log(x) // this prints borked!
}).run()

process.nextTick(function() {
  x = "borked!"
})

// as opposed to this

var x
(function() {
  x = 5
  sleep(0, function() {
    console.log(x) // this also prints borked! which isn't as surprising 
  })
}())

process.nextTick(function() {
  x = "borked!"
})