2019-06-13 admin


什么是sync-p,A tiny sync promise lib



A tiny sync promise lib


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


npm install sync-p


var Promise = require('sync-p')

var result
var p = new Promise(function (resolve, reject) {
    // resolve immediately
  .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 () {
  }, 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]

// ... etc.


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)

run tests

npm test

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