refcount

count things on an observable stack

installation

$ npm install refcount

usage

let's say you're streaming some things

stream.on('data', function (x) {
  // do stuff async with x
})

and you want to add a final step after all the async stuff is done. With refcount, we can keep track of how many requests we've sent off and be notified when they've all been handled:

var refcount = require('refcount')

var counter = refcount()

stream.on('data', function (x) {
  counter.push()
  doStuff(x, function () {
    counter.pop()
  })
})

counter.on('clear', function () {
  console.log('we\'re all done here!')
})

We can check the current counter number like so:

counter.i

It also keeps track of the high water mark, that is, the highest value the counter ever reached:

var counter = refcount(20)
counter.pop(15)

counter.i
// => 5

counter.highwater
// => 20

We can also listen for push and pop events using the standard EventEmitter interface:

counter.on('push', function () {
  console.log('add one')
})

counter.on('pop', function () {
  console.log('subtract one')
})

For memory purposes, consider using .once:

counter.once('clear', function () {
  console.log('done')
})

api

refcount(), refcount(initial : Number)

Initializes a new refcounter. If an initial count is not specified, it defaults to 0.

refcount#push(), refcount#push(delta : Number)

Increments the count by 1 or delta. Returns the current counter value.

refcount#pop(), refcount#pop(delta : Number)

Decrements the count by 1 or delta, to a minimum of 0. Returns the current counter value.

refcount#i : Number

The current counter value

refcount#highwater : Number

The highest counter value

events

clear: no arguments

Fires when a .pop operations results in the counter getting down to zero.

push: delta : Number, totalCount : Number

Fires after a push event. delta is the number added to the total count, and totalCount is the new total after the push operation.

pop: delta : Number, totalCount : Number

Fires after a pop event. delta is the number subtracted from the total count, and totalCount is the new total after the pop operation.

running the tests

$ npm test

contributors

jden [email protected]

license

MIT. (c) 2013 Agile Diagnosis [email protected]. See LICENSE.md