Promises Async Await & Callback

JavaScript Promises, callback and async-await
javascript immutability and javascript Objects
understanding javascript callback, writing promises and async-await

#programming #developer #python

What is GEEK

Buddha Community

Understanding JavaScript: Promises, Async & Await!!

Analogy

We all know the importance of promises in our life. We even have a special day dedicated to it :) But how well do we know the importance of promises in JavaScript? Well if you don’t know it yet, it’s a great time to know it because they are becoming more and more popular. So what are promises? Let’s try to understand it through an analogy.

Suppose you are a top class rapper and you haven’t released an album for a while and fans are asking for it day and night. So what you do is that you “promise” them that whenever it will be out, all of them would be notified. To get this done you give your fans a list. They can fill in their email addresses, so that when the album becomes available, all the subscribers instantly receive it. And even if something goes wrong, say a pandemic, so that you can’t release the album, they will still be notified.

Now everyone is happy: You, because the people don’t crowd you anymore, and fans, because they won’t miss any news on the album.

This is a real-life analogy for things we often have in programming:

1. A “producing code” that does something and may take time. That’s a “rapper”.
2. A “consuming code” that wants the result of the “producing code” once it’s ready. Many functions may need that result. These are the “fans”.
3. A promise is a special JavaScript object that links the “producing code” and the “consuming code” together. In terms of our analogy: this is the “subscription list”. The “producing code” takes whatever time it needs to produce the promised result, and the “promise” makes that result available to all of the subscribed code when it’s ready.

JavaScript promises are much more complex than a simple subscription list: they have additional features and limitations. But it’s fine to begin with.

#async #promises #javascript #development #await

React Async Await Fetch Api Call Example

https://www.codecheef.org/article/react-async-await-fetch-api-call-example

#react #fetch-api #async #await #async-await

JavaScript Fetch API Explained | Callbacks, Promises, Async Await

Learn about Callbacks, Promises, and Async Await as the JavaScript Fetch API is explained in this tutorial. You will also learn about thenables and how async / await replaces them in our JS code. The first 30 minutes covers the concepts. The last 30 minutes gives examples of retrieving data from different APIs with Fetch.

Quick Concepts outline:
Fetch API with Async / Await
(0:00) Intro
(0:29) What is a callback function?
(1:15) What is the problem with callbacks?
(3:00) JavaScript Promises have 3 states
(5:28) A promise may not return a value where you expect it to: You need to wait for a promise to resolve
(6:58) Using thenables with a promise
(20:15) An easy mistake to make with promises
(24:00) Creating an async function
(25:00) Applying await inside the function
(33:45) Example 1: Retrieving user data
(40:00) Example 2: Retrieving dad jokes
(47:00) Example 3: Posting data
(49:40) Example 4: Retrieving data with URL parameters
(54:55) Abstract it all into single responsibility functions

Subscribe: https://www.youtube.com/c/DaveGrayTeachesCode/featured 

#async  #await  #fetch #javascript 

Callback vs Promises vs Async Await

Learn fundamental concepts that JavaScript relies on to handle asynchronous operations. These concept includes Callbacks, Promises and the use of Async and Await to handle deferred operations.

https://www.loginradius.com/engineering/blog/callback-vs-promises-vs-async-await/

#javascript #callback #asyncwait #promises

What is promise and Async/Await?

Base on developer requirement we are going to cover promises and async/await with this article. Some developers are still confused about how to use promises and async javascript. JavaScript Promises are very similar to real-life promises made by us. After that promises, we make a plan and assure that we are successfully have done or broke.

JS promises are completion or failure.

#async #await #javascript #js