Deferred objects

Deferred objects and their promises allow us to react to the completion of long-running tasks with a convenient syntax. They are discussed in detail in Chapter 11.

Object creation

Function	Description
$.Deferred([setupFunction])	Returns a new deferred object
$.when(deferreds)	Returns a promise object to be resolved when the given deferred objects are resolved

Methods of deferred objects

Method	Description
.resolve([args])	Sets the state of the object to resolved
.resolveWith(context, [args])	Sets the state of the object to resolved, while making the keyword this refer to context within callbacks
.reject([args])	Sets the state of the object to resolved
.rejectWith(context, [args])	Sets the state of the object to resolved, while making the keyword this refer to context within callbacks
.promise([target])	Returns a promise object corresponding to this deferred object

Methods of promise objects

Method	Description
.done(callback)	Execute callback when the object is resolved
.fail(callback)	Execute callback when the object is rejected
.always([callback])	Execute callback when the object is resolved or rejected
.then(doneCallbacks, failCallbacks)	Execute doneCallbacks when the object is resolved, or failCallbacks when the object is rejected
.isRejected()	Return true if the object has been rejected
.isResolved()	Return true if the object has been resolved
.pipe([doneFilter], [failFilter])	Return a new promise object which is resolved when the original promise is, optionally after filtering the object's status through a function