JS Callback vs Promises vs Async Await 2

Using Promise:

To use the above create Promise we use then() for resolve and catch() for reject.

let’s take this a step further:

In our created promise condition is “true” and we call demoPromise() then our console logs read:

So if the promise gets rejected, it will jump to the catch() method and this time we will see a different message on the console.

What is Chaining?

Sometimes we need to call multiple asynchronous requests, then after the first Promise is resolved (or rejected), a new process will start to which we can attach it directly by a method called chaining.

So we create another promise:

We chain this promise to our earlier “myFirstPromise” operation like so:

Since our condition is true, the output to our console is:

Once the “hello” promise is chained with .then, subsequent .then utilizes data from the previous one.

Async/Await:

Await is basically syntactic sugar for Promises. It makes your asynchronous code look more like synchronous/procedural code, which is easier for humans to understand.

Syntax of Async and Await:

You can see that we use the “async” keyword for the wrapper function printMyAsync. This lets JavaScript know that we are using async/await syntax, and is necessary if you want to use Await. This means you can’t use Await at the global level. It always needs a wrapper function. Or we can say await is only used with an async function.

Thank you