Bare bones Promises/A+ implementation
This a bare bones Promises/A+ implementation.
It is designed to get the basics spot on correct, so that you can build extended promise implementations on top of it.
$ component install then/promise
$ npm install then-promise
In the example below shows how you can load the promise library (in a way that works on both client and server). It then demonstrates creating a promise from scratch. You simply call
new Promise(fn). There is a complete specification for what is returned by this method in Promises/A+. The resolver object has two methods
fulfill and their use is demonstrated here:
var Promise = require'then-promise';var promise =get''if err resolverrejecterr;else resolverfulfillres;;;
There are two options for extending the promises created by this library.
You can use inheritance if you want to create your own complete promise library with this as your basic starting point, perfect if you have lots of cool features you want to add. Here is an example of a promise library called
Awesome, which is built on top of
var Promise = require'then-promise';Promisecallthis fn;;Awesome;//Awesome extensionreturn thisthenreturn cbapplythis arr;;
N.B. if you fail to set the prototype and constructor properly or fail to do Promise.call, things can fail in really subtle ways.
In general, you should never extend the prototype of this promise implimenation because your extensions could easily conflict with someone elses extensions. However, this organisation will host a library of extensions which do not conflict with each other, so you can safely enable any of those. If you think of an extension that we don't provide and you want to write it, submit an issue on this repository and (if I agree) I'll set you up with a repository and give you permission to commit to it.