This is a strictly-compliant Promises/A+ 1.1.1 implementation in just 2KB of (compressed) code, which passes the official Promises/A+ Test-Suite and includes back-references to the relevant specification statements. It just provides a minimum Promise functionality, because it is intended to be directly embedded into ECMAScript 5 based libraries and frameworks, in order to dependency-free leverage from Promises and be able to return "thenable" Promise objects to applications. As such, it only provides the bare Promise creation and resolving functionalities and no general Promise management functionalities. For applications (and similar contexts where extra dependencies do not matter), please use a full-featured Promise library like Bluebird or any of the other Promise/A+ compliant implementations instead. Then to use Thenable you can do either...