Promise.all In JavaScript Explained

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What arePromisesinJavascript?

According to MDN The Promise object represents the eventual completion (or failure) of an asynchronous operation and its resulting value.

Promise.All

Introduction to Promises in JavaScript

When I first came across the need to fetch user data and the data from sheets simultaneously, It was when the Promise.all proved advantageous. Let me tell you, it was a revelation! In this article, I'll take you through my journey with Promise.all and how it transformed the way I approach coding. Get ready to Learn Promise.all in a concise way and elevate your development game!

Understanding Promise.all
When in needs of calling multiple API simultaneously, Promise.All becomes invaluable. By bundling all promises into a single array, it enables parallel processing, which in turn makes it asynchronous and also significantly reducing processing time.

Practical Example

Here's an example for a better understanding.

Let's say we have four API calls.
Promise.all([first, second, third, fourth])and this will take 1s, 2s, 4s and 3s respectively to return the API calls.
So, if that's the case and all the promises were successful can you guess what will be the output?
Yeah, you guessed it right. It will be an array with the result of all these promises [result1,result2,result3,result4].

So, now you might wonder whether they will all resolve at the same time or at different times?
The promise.all works in a way that it will wait until all the promises are resolved. Therefore, in the above scenario it will take four second to return the result.

But what happens if any one of them are rejected?
For instance, if any one of the promises were to be rejected. Let's say the second promise which takes 2s is rejected then it will throw an error immediately without waiting for other promises to resolve. In such scenarios promise.all will return an error.

Conclusion

Promises in JavaScript enables asynchronous programming to be handled in a more efficient and cleaner method compared to callbacks. By understanding the features of Promises like Promises.all you can write more advanced and efficient codes that run smoothly. Keep practicing do your own examples with Promises.all to get a clarity on it. Keep practicing. Happy Coding!!

Thank You for reading this. More Contents To Come. Stay Tuned!