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A solid, fast Promises/A+ and when() implementation, plus other async goodies.

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README.md
apply.js
cancelable.js
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delay.js
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timed.js
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when.js

README.md

Build Status

A lightweight CommonJS Promises/A and when() implementation. It also provides several other useful Promise-related concepts, such as joining and chaining, and has a robust unit test suite.

It's just over 1k when compiled with Google Closure (w/advanced optimizations) and gzipped.

when.js was derived from the async core of wire.js.

What's New?

when.js.next

  • when.resolve() - creates a resolved promise. See API docs below.
  • deferred.resolve and deferred.reject now return a promise.
  • deferred.resolve(promise) puts the deferred into the same state with the same value as promise.

Full Changelog

Docs & Examples

API docs

More info on the wiki

Examples

Quick Start

AMD

  1. git clone https://github.com/cujojs/when or git submodule add https://github.com/cujojs/when
  2. Configure your loader with a package:

    packages: [
        { name: 'when', location: 'path/to/when/', main: 'when' },
        // ... other packages ...
    ]
  3. define(['when', ...], function(when, ...) { ... }); or require(['when', ...], function(when, ...) { ... });

Script Tag

  1. git clone https://github.com/cujojs/when or git submodule add https://github.com/cujojs/when
  2. <script src="path/to/when/when.js"></script>
  3. when will be available as window.when

Node

  1. npm install when
  2. var when = require('when');

RingoJS

  1. ringo-admin install cujojs/when
  2. var when = require('when');

Running the Unit Tests

Install buster.js

npm install -g buster

Run unit tests in Node:

  1. buster test -e node

Run unit tests in Browsers (and Node):

  1. buster server - this will print a url
  2. Point browsers at /capture, e.g. localhost:1111/capture
  3. buster test or buster test -e browser

References

Much of this code was inspired by @unscriptable's tiny promises, the async innards of wire.js, and some gists here, here, here, and here

Some of the code has been influenced by the great work in Q, Dojo's Deferred, and uber.js.

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