Episode 333

JSJ 329: Promises, Promise.finally(), and Async/await with Valeri Karpov


September 4th, 2018

1 hr 8 mins 31 secs

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About this Episode


  • Charles Max Wood
  • AJ O’Neal
  • Aimee Knight

Special Guests: Valeri Karpov 

In this episode, the panel talks with programmer, Valerie Karpov from Miami, Florida. He is quite knowledgeable with many different programs, but today’s episode they talk specifically about Async/Await and Promise Generators. Val is constantly busy through his different endeavors and recently finished his e-book, “Mastering Async/Await.” Check-out Val’s social media profiles through LinkedIn, GitHub, Twitter, and more.

Show Topics:

1:20 – Val has been on previous episodes back in 2013 & 2016.

1:37 – Val’s background. He is very involved with multiple companies. Go checkout his new book!

2:39 – Promises generators. Understand Promises and how things sync with Promises. Val suggests that listeners have an integrated understanding of issues like error handling.

3:57 – Chuck asks a question.

6:25 – Aimee’s asks a question: “Can you speak to why someone would want to use Async/Await?”

8:53 – AJ makes comments.

10:09 – “What makes an Async/Await not functional?” – Val

10:59 – “What’s wrong with Promises or Async/Await that people don’t like it?” - AJ

11:25 – Val states that he doesn’t think there really is anything wrong with these programs it just depends on what you need it for. He thinks that having both gives the user great power.

12:21 – AJ’s background is with Node and the Python among other programs.

12:55 – Implementing Complex Business Logic.

15:50 – Val discusses his new e-book.

17:08 – Question from Aimee.

17:16 – AJ answers question. Promises should have been primitive when it was designed or somewhat event handling.

17:46 – The panel agrees that anything is better than Call Backs.

18:18 – Aimee makes comments about Async/Await.

20:08 – “What are the core principles of your new e-book?” – Chuck

20:17 – There are 4 chapters and Val discusses, in detail, what’s in each chapter.

22:40 – There could be some confusion from JavaScript for someone where this is their first language. Does Async/Await have any affect on the way you program or does anything make it less or more confusing in the background changes?

24:30 – Val answers the before-mentioned question. Async/Await does not have anyway to help with this (data changes in the background).

25:36 – “My procedural code, I know that things won’t change on me because it is procedural code. Is it hard to adjust to that?” – AJ

26:01 – Val answers the question.

26:32 – Building a webserver with Python

27:31 – Aimee asks a question: “Do you think that there are cases in code base, where I would want to use Promises? Not from a user’s perspective, but what our preferences are, but actual performance. Is there a reason why I would want to use both or be consistent across the board?”

28:17 – Val asks for some clarification to Aimee’s question.

29:14 – Aimee: “My own personal preference is consistency. Would I want to use Promises in ‘x’ scenario and/or use Async/Await in another situation?”

32:28 – Val and AJ are discussing and problem solving different situations that these programs

33:05 – “When would you not want to use Async/Await?” – AJ

33:25 – Val goes through the different situations when he would not use Async/Await. 

33:44 – Chuck is curious about other features of Async/Await and asks Val.

36:40 – Facebook’s Regenerator

37:11 – AJ: “Back in the day, people would be really concerned with JavaScript’s performance even with Chrome.” He continues his thoughts on this topic.

38:11 – Val answers the AJ’s question.

39:10 – Duck JS probably won’t include generators.

41:18 – Val: “Have anyone used Engine Script before?” The rest of the panel had never heard of this before.

42:09 – Windows Scripting Host

42:56 – Val used Rhino in the past.

43:40 – Val: “Going back to the web performance question...”

47:08 – “Where do you see using Async/Await the most?” – Chuck

47:55 – Val uses Async/Await for everything on the backend because it has made everything so easy for him.

48:23 – “So this is why you really haven’t used Web Pack?” – AJ

49:20 – Let’s go to Aimee’s Picks!

50:18 – AJ’s story, first, before we get to Promises.

54:44 – Let’s transition to Promises Finally.

54:53 – Val talks about Promises Finally.

59:20 – Picks