Tutorials

jQuery deferred Objects

Posted in jQuery Tutorial

Updated on Aug 17, 2024

By Mari Selvan

👁️ 72 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

Explore the power and flexibility of jQuery Deferred, a key component for managing asynchronous operations in JavaScript. Learn how this feature enables efficient handling of asynchronous tasks, making your code more organized and responsive.

🤔 What is jQuery Deferred?

jQuery Deferred is an object that signifies the eventual completion or failure of an asynchronous operation. It plays a crucial role in simplifying the handling of asynchronous tasks by allowing you to attach multiple callbacks that execute when the operation is successfully completed or encounters an error.

🗝️ Key Features

Asynchronous Operation Control:

jQuery Deferred provides a structured approach to control the flow of asynchronous operations, making it easier to manage complex tasks.
Callback Attachment:

With Deferred, you can attach callbacks that execute when the operation is resolved (successfully completed) or rejected (encounters an error). This facilitates better organization of your code.
Promise Integration:

Deferred objects can be converted into Promises, allowing limited access to their state. This integration enhances compatibility with modern JavaScript practices.

📝 List of Deferred Objects

The following are the list of Deferred Objects:

Functions	Explanation
deferred.always()	Add handlers for when the Deferred object is resolved or rejected.
deferred.catch()	Add handlers for when the Deferred object is rejected.
deferred.done()	Add handlers for when the Deferred object resolves.
deferred.fail()	Add handlers for when the Deferred object is rejected.
deferred.isRejected()	Check if a Deferred object was rejected.
deferred.isResolved()	Check if a Deferred object is resolved.
deferred.notify()	Invoke the progressCallbacks on a Deferred object with the provided args.
deferred.notifyWith()	Invoke progressCallbacks on a Deferred object with the provided context and args.
deferred.pipe()	Utility to filter and/or chain Deferreds.
deferred.progress()	Add handlers for progress notifications generated by the Deferred object.
deferred.promise()	Return a Deferred's Promise.
deferred.reject()	Reject a Deferred object and invoke failCallbacks with the provided arguments.
deferred.rejectWith()	Reject a Deferred object, triggering failCallbacks with the specified context and arguments.
deferred.resolve()	Trigger the execution of a Deferred object, invoking any doneCallbacks with the specified arguments.
deferred.resolveWith()	Resolve a Deferred object, invoking doneCallbacks with the provided context and args.
deferred.state()	Check the Deferred object's current state.
deferred.then()	Add handlers for when the Deferred object is resolved, rejected, or still in progress.
jQuery.Deferred()	A factory function returns a chainable utility object for registering callbacks, invoking queues, and relaying function states.
jQuery.when()	Enables executing callback functions based on zero or more Thenable objects, typically Deferred objects representing asynchronous events.
.promise()	Return a Promise object to track the completion of all actions, queued or not, of a specific type bound to the collection.

📚 Use Cases

Ajax Requests:

Handle asynchronous requests to a server efficiently, ensuring proper execution of code upon successful retrieval or in case of errors.
Animation Sequences:

Create smooth animation sequences by coordinating the execution of code when animations complete or if errors occur.
Complex Workflows:

Manage intricate workflows where tasks depend on the completion of other asynchronous operations.

🌟 Advantages

Code Organization:

Deferred promotes cleaner and more organized code, especially in scenarios involving multiple asynchronous tasks.
Error Handling:

Effectively handle errors in asynchronous operations by attaching error callbacks to Deferred objects.
Promise Compatibility:

Deferred seamlessly integrates with Promises, allowing you to embrace modern JavaScript practices and libraries.

🎉 Conclusion

jQuery Deferred is a powerful tool for handling asynchronous tasks in JavaScript, offering a structured and efficient way to manage code execution upon completion or failure of operations. Whether you're working with Ajax requests, animations, or complex workflows, understanding Deferred is key to writing robust and responsive code.