sync-p

A tiny sync promise lib

features

sync-p is 55 lines of code, but handles the majority of the promise spec. Some of the spec is intentionally avoided, e.g.

• sync-p is capable of returning synchronously, i.e. it does not defer everything
• to avoid bloat sync-p assumes that truthy args passed to .then are functions (strict adherence involves explicitly handling cases like .then(5) ...like, just don't do that, that's not the api)
• it does not throw if a promise is rejected and no reject handler is attached

installation

npm install sync-p

usage

var Promise = require('sync-p')

var result
var p = new Promise(function (resolve, reject) {
    // resolve immediately
    resolve(true)
  })
  .then(null, null)
  .then(function (val) {
    result = val
  })
console.log(result) // true

new Promise(function (resolve, reject) {
  throw 'error'
})
.catch(function (err) {
  console.log(err) // 'error'
})

var p = new Promise(function (resolve, reject) {
  setTimeout(function () {
    resolve(true)
  }, 0)
})
.then(onSuccess, onError)

var all = require('sync-p/all')

var p = all([1, 2, promise3]).then(function (val) {
  console.log(val) // [1, 2, 3]
})

var p = any([promise1, promise2, 3]).then(function (val) {
  console.log(val) // 3
})

var p = any([promise1, promise2, promise3]).catch(function (err) {
  console.log(err) // [err1, err2, err3]
})

// ... etc.

extra

var Promise = require('sync-p/extra')

// includes all, resolve, reject and defer
var promise = Promise.all(array)
var resolved = Promise.resolve(123)
var rejected = Promise.reject(321)
var deferred = Promise.defer()
var race = Promise.race(array)
var any = Promise.any(array)

run tests

npm test

Want to work on this for your day job?

This project was created by the Engineering team at Qubit. As we use open source libraries, we make our projects public where possible.

We’re currently looking to grow our team, so if you’re a JavaScript engineer and keen on ES2016 React+Redux applications and Node micro services, why not get in touch? Work with like minded engineers in an environment that has fantastic perks, including an annual ski trip, yoga, a competitive foosball league, and copious amounts of yogurt.

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