This community-built FAQ covers the “The async Keyword” exercise from the lesson “Async Await”.
Paths and Courses
This exercise can be found in the following Codecademy content:
Web Development
Asynchronous JavaScript
FAQs on the exercise The async Keyword
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async function withAsync(num){
if (num === 0){
return 'zero';
} else {
return 'not zero';
}
}
withAsync(100)
.then((resolveValue) => {
console.log(` withAsync(100) returned a promise which resolved to: ${resolveValue}.`);
})
after calling withAsync(100) why don’t we include also .catch() as a rejected outcome. Or why do we only use .then()?
7 Likes
Why use Promise over async…await?
is it just for compatibility at this point? Or are there benefits to using Promise
5 Likes
It’s just so annoying when you get the exercise right, but codecademy won’t take your answer for some reason. I press get solution to this, code is identical fml.
6 Likes
I don’t think there’s any real advantage, just syntactic sugar - easier to read and understand.
I think that lower part would be better written with await inside withAsync’s body. It’s probably just a placeholder before await is introduced.
What is meant by:
If there’s a non-promise value returned from the function, it will return a promise resolved to that value.
What’s the difference between a value and a promise resolved to a value?
For once, I think the course is well made.
I followed another one on this topic and it was really confusing…
async function withAsync(number) {
return number ? "not zero" : "zero";
}
2 Likes
Is it not possible to combine async with an arrow function?
I tried:
async const withAsync = num => {
if (num === 0) {
return 'zero';
} else {
return 'not zero';
}
}
But unexpected token on const and then I tried:
async withAsync = num => {
if (num === 0) {
return 'zero';
} else {
return 'not zero';
}
}
Unexpected identifier on withAsync, so I guess not…
It seems like we need to declare async on the function, rather than the variable, so if we wanted to use it with arrow functions then we’d put:
const withAsync = async num => {
}
See:
4 Likes
Is it normal in the example we have two “resolve” as argument and not reject if it’s not equal to zero?
function withConstructor(num){
return new Promise((resolve, reject) => {
if (num === 0){
resolve('zero');
} else {
resolve('not zero');
}
})
}
withConstructor(0)
.then((resolveValue) => {
console.log(` withConstructor(0) returned a promise which resolved to: ${resolveValue}.`);
})
2 Likes
The difference is not in the outcome but in the process the computer took to returns that value.
For instance the following will return the same value but the process is different:
onsole.log(3)
console.log(1+2)
I prefer using the ternary operator! i think its easier 
1 Like
We don’t have 2 resolved values, but 1 which depends on a condition. The reason we aren’t rejecting a value is because we aren’t handling errors at the moment. We are simply saying “If the num argument is equal to 0, return this resolved value, and if it’s not equal to 0, return this resolved value”
If you wanted to take it a step further, you could use the reject function to return an error if the num argument isn’t a number. To achieve this, you could do something like this:
function withConstructor(num){
return new Promise((resolve, reject) => {
if (typeof num !== "number") {
reject("Error: passed in argument isn't of type 'number'")
} else if (num === 0){
resolve('zero');
} else {
resolve('not zero');
}
})
}
2 Likes
Yes, happens more often than one would think. Copy your code, reset the exercise, and paste. It’s second nature to me now.
OK this has happened on EVERY SINGLE EXERCISE from
Whenever i try to run node I get this error
and everytime I spend a while scratching my head, going through every line of code looking for the difference to the solution and finding there is none, but the only thing that fixes it is replacing my code with solution button.
AFAICS my code is identical, but I will have to replace it to get it to work.
Edit. Saw someone else’s solution to copy work, refresh page and paste back in. It works, but something is definitely going wrong with your node js.
4 Likes
As said the intro, Promise is ES6 while async/await is ES8. It’s a pure syntactic choice. Your Babel transpiler will convert it into ES5 in both cases.
I’m getting this regularly too. I think my internet connection drops periodically, which is causing this. I would say it’s a bug on Codecademy’s side.
1 Like
I really liked this lesson. Nicely explained and boy does async make things easier
Hello uzikim1, how are you? 
I’m Brazilian, and my English isn’t perfect, but if you can understand me, that’s cool!
Unlike a promise that returns a resolved or rejected value depending on conditions, async only returns ‘resolved’ values. If you add a catch, it will not return any value for the argument!
2 Likes
