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Simply Deferred

jQuery-like Deferred API for Node and the browser

Simply Deferred is now feature complete. Bug fixes will be made, but no API changes are expected unless they're to ensure compliance with the jQuery API.


npm install simply-deferred


var Deferred = require('simply-deferred').Deferred;
var rendering = new Deferred();
    console.log('Finished rendering');




Simply Deferred is fullly compatible with jQuery's API, so the docs and usage are the same. Like the jQuery deferred API, it provides the following methods:

  • Deferred()
  • deferred.state()
  • deferred.done()
  • deferred.progress()
  • deferred.always()
  • deferred.promise()
  • deferred.notify()
  • deferred.notifyWith()
  • deferred.resolve()
  • deferred.resolveWith()
  • deferred.rejectWith()
  • deferred.reject()
  • deferred.pipe()
  • deferred.then()
  • Deferred.when()


Please feel free to raise issues on - both obvious bugs or incompatibilities with jQuery are welcome.

If you'd like contribute a fix or a feature, that would be even better. Please make sure all pull requests are accompanied by tests, though.

If you'd like to start work on a feature that is not part of the jQuery library, just raise an empty pull request and let's talk about it first - the goal here for this library to be a drop-in replacement for jQuery, with the same docs and API.

Usage with Zepto

Zepto now has a deferred module available, so you might want to use that if Zepto is your primary reason for using Simply Deferred.

Simply Deffered also acts as a plugin to Zepto. The absence of a Deferred library was one of the biggest reasons I've been holding back, so I thought it made sense to write one. Once you have both Zepto and Simply Deferred on your page, just do Deferred.installInto(Zepto) to set it up. The installation makes the following changes to bring it closer to jQuery:

  • Aliases the Deferred constructor to $.Deferred.
  • Aliases the when method to $.when.
  • Wraps $.ajax to return a promise, which has only the following methods: state(), done(), fail() and always(). The arguments passed to the done and fail callbacks are the same ones passed to the success and error options.