An interesting little demo to demonstrate some of the intricacies and changes with the Node.js event loop

eventloop.js

var counter = 0

var start = Date.now()

function foo(from, when) {
  console.log(counter, when, from, process._getActiveHandles().length, Date.now() - start)
  counter++

  var scheduledAt = counter
  if (counter == 2 || counter == 25) {
    process.nextTick(function () {
      foo("nextTick", scheduledAt)
      setImmediate(foo, "nextTick->setImmediate", scheduledAt)
    })
  }
  else if (counter == 6) {
    setTimeout(function () {
      foo("setTimeout", scheduledAt)
      setImmediate(foo, "setTimeout->setImmediate", scheduledAt)
    }, 0)
  }
  if (counter < 25) {
    setImmediate(foo, "foo", scheduledAt)
  }
}

foo("root", counter)