asynchronous-javascript-event-loop-callbacks-promises-async-await/

[utterances-bot]

Understanding the Event Loop, Callbacks, Promises, and Async/Await in JavaScript | Tania Rascia

This article was originally written for DigitalOcean. Introduction In the early days of the internet, websites often consisted of static…

https://www.taniarascia.com/asynchronous-javascript-event-loop-callbacks-promises-async-await/

[markomeje]

Very explanatory. Thank you and keep it up.

[ephraimduncan]

Thank You.

[kemalgencay]

Wonderful article, thank you,

[mshams999]

Nice

[LissetteIbnz]

Great!

[VikR0001]

I'm reading your article and learning a lot! I have a quick question. A lot of my code has this:

            return Promise.resolve()
                .then(() => {
                    let objectFromDatabase = connectors.myTable.findOne({
                        where: {id: objectId}
                    });
                    return objectFromDatabase;
                })
                .catch((err) => {
                    console.log(err);
                });

...this works fine. My question is, do I need to be doing:

         return new Promise.resolve()

....instead of:

        return Promise.resolve()

And if not, why not if I may ask? Thanks very much in advance for any thoughts / info!

[philsav]

Very good article, just need to know is which scenario to use promise and which to use async/await, Is promises used when multiple promises need to be checked using promise all, is there also a await all

[astrit]

What a detailed explanation, learned a-lot from it. thank you

[KVNEZE]

This is a really well written article, I connected dots that I didn't know I needed to connect.

Thank you.

[andrebonfimdev]

Great article. Congratulations!

[moofoo]

Concise and informative.

[yonycalsin]

Nice 👍

[pb03]

Nicely explained. Maybe little more explicit here in the Queue section:

but that it will add the anonymous function to the queue in that amount of time.

Web API will add this function to the queue (not directly from the stack)

[DrWongKC]

Thank you so much for writing this. You're an incredibly teacher. :) I hope you keep writing about programming, even after you decide to retire. It's really helping me.

[liwei766]

Good personal blog! Static site and commenting system works.

[kusaljay]

Thanks for this article. Can you please write a one for Closures?

[sddania]

@VikR0001

My question is, do I need to be doing: return new Promise.resolve() instead of: return Promise.resolve()

as Promise doc says, the resolve method is static and you dont need to instantiate a new Promise to call it.

if you want to use Promise as object you can wrap functions that do not already support promises on Promise constructor:

const promise = new Promise( (res ,rej) => {
    res("hello!")
} )
promise.then(val => console.log(val))

the console will show "hello!"

[pedegago]

Great article. I was reading it for some days in order to understand everything!

[hunzaboy]

Tania, thanks for the great article. I really enjoy your writing style. Simple with full of knowledge.

[immaithil]

It was a great article finally I am able to clear confusion about .then and .catch.

[alex-j-garcia]

Thanks for the great article. Some things didn't make sense right away, but I kept rereading and going through your examples until it clicked!

[aakinlalu]

Thank you

[sanfordstaab]

I'm trying to use a promise or async/await to create a modal dialog API that returns information synchronously but I don't know how to un-stack the promise so that a click event triggers the resolution of the promise except by some kind of setTimeout(forever) hack. I want a simply synchronous api like:

---

// in the middle of some complex nested operation where callbacks just suck ... const btnText = await msgBox([ 'Yes', 'No', 'Maybe' ], 'Text of messagebox'); if (btnText == 'Maybe') { ....

---