Creating JavaScript Promises

Not only do you need to know how to use promises, there are times you will need to create a promise. In this tutorial we walk through the process of creating a promise.

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Tutorials referred to in this video:

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[lucksmith-wd]

Thank you! THANK YOU! I very rarely comment on videos, but this is just pure gold! It's not an easy concept, and you understand how much beginners may struggle with it. That's why your explanation is so clear. Thank you, again!

[MeAsMeButMe]

You're a very skilled teacher! Thanks, I really appreciate these videos!

[yaolu]

This is just too good. I have to admit I did'nt understand this concept from the tutorial bought from Udemy, thanks for your generousity and selflessness!

[chnsonic]

Oh, it's the best js promise lesson I ever seen!

[someoneoutthere]

Having fun rewriting this in ES6:
a.then(val => {console.log(val)}, (val) => {console.log("rejected: "+ val)});

[michellanea_]

Thank you so much! This definitely helped me in my overall understanding promises and using them for a bootcamp project due next week...!

[pravinkolambkar]

You r great teacher. But the problem is promises is really very difficult topic. So can you make few more tutorials on this

[MrMarkgyuro]

if somebody wanna use the last part with arrow syntax:


let setTimeoutPromise = (time) => {
return new Promise( (resolve, reject) => {
if (isNaN (time)) {
reject('a number is required\n please fill it again below')
}
setTimeout(resolve, time)
})
}

setTimeoutPromise('kami')
.then( () => {
console.log('done')
})
.catch( (error) => {
console.log(error)
})

[khorajia]

What is the difference between 'new Promise' and 'return new Promise'?
Also you have written resolve with parenthesis "resolve()" and also without parenthesis "resolve". What is the difference here?
Thank you for this tutorial.

[tusharubale]

Please explain what this line of code does

let promise =


});

What is the role of executor function in this context? how does it get called in back? what does it return ?

[sevdamurat]

When I use setTimeout as: setTimeout(resolve("done"), 4000); --> this time it doesnt wait!! Why?