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Asynchronous JavaScript: Promises, Callbacks, Async Await (Udemy.com)

Become an expert in Asynchronous JavaScript: Promises, Callbacks, Async Await, Event Loop, etc.

4.6
2,781 reviews

Created by: Viktor Pyskunov

Last updated May 2026

Our take

Based on the ratings of 2,781 students, a sample of their written reviews and the syllabus, as the course stood in May 2026. No course pays to be reviewed.

This is a short, focused course on one topic: how asynchronous code works in JavaScript. Viktor Pyskunov splits it into callbacks, promises, async await and a closing section on the event loop, plus two short sections on testing async code. It runs about 4.9 hours across 59 lectures, and promises take the biggest share at roughly two hours. It was last updated in May 2026, so it is not stale. It assumes you already know basic JavaScript.

Reviewers like the drawn diagrams and animations, and a few say it made promises and the event loop clearer than other sources had. Some praise the short, well organized lectures. About 61 percent of the 2,781 ratings are five stars. Complaints are practical. Two reviewers want more realistic examples, one calls it a little boring, and a few mention a strong accent or weak audio. One reviewer says the environment setup was not explained clearly. There are no quizzes or coding exercises.

The course has about 14,800 students and does one job. One reviewer who already knew promises said any YouTube video could cover the same ground, and that is fair. For someone shaky on promises or the event loop, it is a quick, clear fix. Others with experience still recommend it, but anyone wanting practice will need to supply their own.

Best forDevelopers with basic JavaScript who want promises and the event loop explained with diagrams in under five hours.
Skip it ifYou want quizzes, coding exercises or realistic production-style examples, since the course has no exercises and reviewers ask for more practical scenarios.

Pros

  • Drawn diagrams and animations make promises and the event loop easier to picture
  • Short, focused lectures: about 4.9 hours total with no filler
  • Two sections on unit testing callbacks and promises, about 40 minutes in all
  • Code repository is included, and the course was refreshed in May 2026

Cons

  • No quizzes or coding exercises, so practice is up to the student
  • Some reviewers find it dry and want realistic, production-style examples
  • A few reviewers struggled with the accent, audio quality or the unclear environment setup
I used to read about asynchronous JS earlier, but I have understand very small piece of information. Here I understand everything better with animations, real world exampled and real-time coding.
Nadejda Socolova, a student

Listed for all levels, but it fits beginners who know basic JavaScript. Total newcomers to code may struggle.

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What you will learn

  • Learn fundamental concepts of Asynchronous JavaScript
  • Everything you need to know about Promises
  • Using Callbacks: Pros and Cons, when to use and how to test them
  • Async / Await - the modern way of handling asynchronous tasks in JavaScript
  • In-depth understanding of the Event Loop
  • Learn how JavaScript Engine executes code behind the scenes
  • Unit Testing of asynchronous functions
  • No fluff, direct and to the point
  • Github repository with all the code included

Course content

9 sections · 59 lectures · 4.9 hours of video 3 articles

  1. 1Introduction 2 free previews2 lectures · 5 min
  2. 2Difference Between Synchronous And Asynchronous Actions 3 free previews6 lectures · 24 min
  3. 3Callbacks In JavaScript 2 free previews8 lectures · 30 min
  4. 4Testing Asynchronous Callbacks2 lectures · 15 min
  5. 5Promises In JavaScript 2 free previews20 lectures · 2.1 hours
  6. 6Testing Promises In JavaScript4 lectures · 24 min
  7. 7Async Await in JavaScript 1 free preview6 lectures · 21 min
  8. 8Advanced Version of Event Loop9 lectures · 53 min
  9. 9Summary2 lectures · 1 min

Who it is for

The instructor says it suits

  • Developers with basic JavaScript knowledge
  • Those who want to master Asynchronous JavaScript, Callbacks, Promises, Async Await

What you need before you start

  • Basics of JavaScript

How it compares

Against the other 239 rated Udemy courses in JavaScript on CourseDuck:

  • Rating4.6 out of 5higher than 70% of them
  • Reviews2,781#49 of 240 by number of reviews
  • Length4.9 hoursshorter than 53% of them
  • Last updatedMay 2026more recently than 93% of them

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Quality Score

Content Quality
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Video Quality
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Qualified Instructor
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Course Depth & Coverage
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Overall Score : 92 / 100

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Course Description

My main goal is to help you master Asynchronous JavaScript. This course was specifically designed for those who want to improve their skills in Callbacks, Promises, Async Await, and Event Loop. This course was designed to be easy to understand, and therefore there are a lot of visuals in it, especially when we are talking about important concepts. You will also see a lot of coding examples along the way.

We will be talking about 3 main components of Async JavaScript: Callback functions, Promises, and Async Await.

Callbacks in JavaScript are used everywhere. Creating event handlers, making HTTP requests, interacting with the DOM, setting timeouts, reading or writing data to the filesystem, working with databases, etc. I am pretty sure you are already using callbacks in your code, but I am not sure if you know how they actually work... Knowing how things really work will help you write your code faster and avoid weird bugs.

Promises were created as a better alternative to callbacks. They don't have drawbacks that callbacks have. JavaScript promises are incredibly helpful when you have several asynchronous operations that depend on each other. However, promises are a new concept which you have to learn, and this course will help you with that.

Async Await is a syntactic sugar around Promises introduced in EcmaScript 8. Before that writing asynchronous code in JavaScript was very different from writing ordinary synchronous code. Async await allows you to structure all your code in a similar way, no matter if it's synchronous or asynchronous.

There is a lot of asynchronous stuff going on in popular JavaScript libraries and frameworks: React, Angular, Vue.js, jQuery, etc. In NodeJS it's almost impossible to write anything without using asynchronous operations. After watching this course you will be able to read and write asynchronous JavaScript code effectively, and you will definitely understand how it works behind the scenes!

P. S. Made in Ukraine
Read More All Levels All Levels product length iconTime: 4.9h

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Instructor Details

Viktor Pyskunov

My name is Viktor and my goal is to help you understand stuff.

I am a Senior Software Developer specializing in JavaScript and various technologies around it.
I have been creating web applications for 19 years.
During these years I acquired a lot of expertise in Software Development industry.
Now I want to share my knowledge with you.

I design my courses so they are easy to understand and to follow,
and I update them regularly in order to keep them up-to-date.

Read More

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Reviews

4.6

2,781 ratings on Udemy

Select a bar to show only those reviews.Select the bar again to show every rating.

Write a review

By Carlos Eduardo Boaventura Silva on 2/5/2026

Gostei bastante do curso, a explicação dos conceitos é algo bem didático, ele literalmente desenhava eles, oque tornou muito mais simples a forma de ver uma promise, os callbacks, oque é e para que serve as funções assíncronas e entre outras coisas, recomendo bastante esse curso!

By Abhinandan Tiwari on 4/30/2024

If you know promises then you can get the same knowledge from some other platform too. This course is good for a fresher who is confused with promises as this course will provide a clear picture of promises with a few examples. But yes it's not that great to buy this course separately you can get the same or better knowledge on any YouTube video too. Also, the audio quality is not that good.

By Naresh Kumar Agarwala on 4/10/2024

Little bit boring and monotonous. More interesting examples. Challenging scenario. Need realistic full fledge example. Need example of production grade code. Need concept of creating separate thread to execute long running task. Wait for the result in separate thread. Required more real/practical examples and scenarios. Also, need bit introduction of successive topics in each chapter and how successive topic will eventually help to achieve final goal with realistic/practical examples. Thanks.

By Anonymized User on 7/28/2023

pace is slower than usual but expected since async is difficult. (Recommend watching at 1.25x speed but thats only me) He has simple examples that are executable if you are tech-savvy enough for your own confirmation and debugging. Overall a great course for review or to let the concepts sink in.

By Roma Sumbadze on 5/4/2023

I highly recommend this course to anyone interested in improving their understanding of async operations and how JavaScript manages various tasks. The course is structured in a way that makes complex concepts easy to understand, thanks to clear examples and engaging animations. Personally, I found the course to be incredibly helpful in improving my own coding skills, and I have already started applying what I learned to my own projects. Overall, this course is a great course to see for anyone looking to improve their JavaScript skills and gain a deeper understanding of how async operations work.

By Daevin Oey on 11/8/2020

I was always mystified by the event loop Viktor cleared everything up for concisely and clearly in just 6 minutes!

By Pramod N on 11/8/2020

Good one. Understood the concept very well.

By Naga Dhulipudi on 10/29/2020

The most helpful course so far on Javascript Main Concept Promises & Async/Await. The whole lifecycle of how they work behind the scenes was a challenge for me to read through documentations. Taking this course has levelled up my idea of them for sure. Its not scary anymore when I see these functions out there.

By Erin O'Connor on 10/24/2020

As I sit here this morning, I realize that it is kind of nice to just have the phone in one hand and coffee and scones in the other. Plus, this instructor has made promises palatable.

By Chuck Todd on 10/19/2020

Excellent presentation of the materials. Provided numerous examples that helped to clarify the material.

By Quanfeng Lu on 10/18/2020

Yes. it is very good!

By Ns on 10/17/2020

Covered the topics well.

Showing 12 of 134 reviews

Asynchronous JavaScript: Promises, Callbacks, Async Await
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  • Video Duration: icon 4.9h
  • Price: $10.99
  • Provider: icon Udemy
  • Updated: icon May 2026
  • Level: All Levels All Levels
  • Language: icon English
  • Certificate: icon Yes
  • Lectures:59 in 9 sections
  • Students:14,800
  • Subtitles:2 languages
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