What is a Promise object in Javascript

JavaScript
1

Hi Friends,

I am struggling hard to understand Promise object in javascript as this has been asked to me multiple times in interview and every time I just pass this question.

I have gone through many articles on google but haven’t got the insight on this topic.

Can you please make me understand and it’s significance.

Thanks,
Ashish

3

Promises are for when you want to delay something until a requirement has been fulfilled.

Some good documentation on promises can be found from the MDN page on promises.

4

Paul, What is the async operations in javascript? like it is said in the documentation “The Promise object is used for asynchronous computations.”

Is it like I have made a ajax request to server and I want to show the loading sign…is it something like that?

5

Asynchronous operations are placed in a queue to be completed later on after the JavaScript has completed.

6

Hi Paul,

Can you provide me examples of async opeations…I am newbie to js.
Thanks!!
Ashish

7

AJAX would be the most obvious example. or anything you do in Node.js

8

As a beginner, the first thing you need to understand is what is going on in the core of most Javascript runtime engines, like in browsers or in Node.js. This video does a pretty good job explaining JS internals, especially the event loop.

Once you get that down and understood, then things like a promises should make a bit more sense. Basically, a promise lets you do asynchronous (and also synchronous) work and gives you the ability to better store and act on the results of that work.

Scott

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9

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