A Deferred object is a mechanism for referencing a value which may (or may not) be available at a later point.
Every so often you might require a group of operations to complete before you continue. These operations might need to happen either in sequence or in any order, but they all have to finish before the code can continue.
Ajax requests are the best examples of Deferred Objects because they're so commonly used. But some other cases for Deferred Objects include file access, web workers or other asynchronous calls.
An interesting use I've toyed with is user interaction. Embedded below is an example that shows how to combine deferred objects with mouse events to create a simple mouse dexterity game.
Your new post is loading...
