in-promise is a minimal Promises/A+ implementation for browsers. ~700 bytes (gzip).

API

It is really minimal, and only provides a ES6 style Promise constructor plus a Promises/A+ compatible Promise#then method:

var p1 = new Promise(function (res, rej) {
  setTimeout(function () {
    res('Hello Promise')
  }, 100)
})
var p2 = p1.then(function (value) {
  console.log(value) // Hello Promise
})

This is no Promise#catch or Promise.all or Promise.race or ... Just Promise#then.

For a polyfill for ES6 Promise, check the es6 branch.