promisize

Easily support both callbacks and promises in your js lib

promisize takes your function's callback argument and returns a new callback with a promise property. When the new callback is called, it either calls the original callback or if no callback was given it fulfills the promise. promisize is lightweight and does not include any promise shims or dependencies but instead uses the globally defined Promise. If Promise is not defined (i.e. no native promise support) then callbacks still work as they would without promisize.

Usage

var promisize = require('promisize')
 
function someAsyncFunction (cb) {
  cb = promisize(cb)
 
  // Do some async stuff then
  setTimeout(function () {
    cb(null, 'foobar')
  })
 
  // Undefined if there is no Promise support
  // or if the original callback was defined
  return cb.promise
}

API

var cb = promisize(function callback (err, result) {})

promisize takes a nodejs style callback and returns another nodejs style callback. When the returned callback is called it either calls the original callback or fulfills the promise but never both.

cb.promise

The returned cb has a promise property that is only defined if the environment has Promise support (i.e. Promise is defined) and the original callback was undefined. When the returned callback is called it fulfills this promise if it is defined or calls the original callback if the promise is undefined.

License

MIT. Copyright (c) Austin Middleton.