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Struggling with Promises? You Are Not Alone!

Somnath Singh on July 03, 2022

Do you like to cook? I’m not sure about you, but I enjoy cooking. I usually cook by myself, although I’m not opposed to having some help. Many tim...

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aayush • Jul 4 '22

This is by far the best article I've read on explaining the concept of promises (I'm sure others will agree). 😊

Thank you so much for taking the time to write this. 🙏

Your hand-drawn illustrations and storytelling are fantastic.

You said you're not a master storyteller, Let me tell you:** You certainly are.**

You are exceptional. 🙌

Anyone can make people believe they are intelligent by rambling on about complicated concepts, but the true genius is the one who can explain these concepts to a child. In this article, you have done just that.

I hope to see you among dev.to top writers.

Gaurav Saini • Jul 4 '22

I’m sorry I didn’t read the full post yet, but just from the first few paragraphs and especially the food ingredient analogy is just too good. I had to stop and write this comment.
I “promise” I’ll read the full post. nervous laughter intensifies 😬

Muhammad Harith Zainudin • Jul 7 '22

so, have you resolved your promise? haha

Gaurav Saini • Jul 8 '22

Haha! yes, I sure did 🙂

peerreynders • Jul 3 '22

Just to add:

When a promise is no longer pending it is considered settled.

Promise.allSettled() - JavaScript | MDN

The Promise.allSettled() method returns a promise that resolves after all of the given promises have either fulfilled or rejected, with an array of objects that each describes the outcome of each promise.

developer.mozilla.org

console.log('Vacuuming');
const promise = Promise.resolve().then(() => console.log('Picking up Milk'));
console.log('Washing the Dishes');
promise.then(() => console.log('Take a break'));
console.log('Done inside');
/* 
  Output:
  "Vacuuming"
  "Washing the Dishes"
  "Done inside"
  "Picking up Milk"
  "Take a break"
*/

It's sometimes useful to remember that just because a promise value has settled doesn't mean that it will immediately get processed if something synchronous is currently being processed. One can then onto an already settled promise but the processing will still occur asynchronously.

Also recursively settling promises is the fastest way to starve the event loop.

𒎏Wii 🏳️‍⚧️ • Jul 4 '22

promise.then(onFulfilled)
promise.catch(onFailure)
// We can write it like this also

promise.then(onFulfilled).catch(onFailure)

It should be pointed out that this isn't actually the same, and may behave differently in certain cases.

Grant Riordan • Jul 7 '22

Great article ! A well rounded way of describing promises. Question - what did you use / how did you create your illustrations / storyboard. Im looking for something myself for my articles (I'm very poor at drawing).

SUCHINTAN DAS • Jul 4 '22

Thanks Somnath, it's a good explanation of promises and the story illustration is really amazing.

Just a small suggestion. Please try to use little bit space between the main headings. It sometimes looks like the whole thing is too much stuff into a small space which can be irritating for a reader who is going through the whole blog.

Hope this helps ✌ !