ES6/7 await for async function

Question

I read about await stop the execution while the promise don't get resolve. I'm trying to do the following in my React-native app:

static async getFromStorage(key) {
  const value = await AsyncStorage.getItem(key);
  console.log(value);
  return value;
}

console.log(Class.getFromStorage("test"));

But I get the following instead of the real value (Chrome didn't allow me to copy the timestamp...):

Promise {_45: 0, _81: 0, _65: null, _54: null} <- this is the console.log after the function
100ms later
REAL_VALUE <- this is the console.log from the function

So why my code not waiting for resolve the promise?

UPDATE

@thedude suggest:

async function waitForStorage() {
   console.log(await getFromStorage());
}
waitForStorage();

The problem with this solution I need it in the class what I want to use. but when I do someVar = await getFromStorage(), I get a 500 error. I can wait for it, because it is 100ms.

For example:

someVar = await getFromStorage("token");
checkToken(someVar);

Are you using a transpilier such as babel? es6/7 is not supported everywhere. The whole point about async await is to write asynchronous code in a synchronous fashion. Nothing after your await statement should be executed until the promise that is being await is either resolved or rejected. — Kyle Richardson
– Kyle Richardson, Commented Apr 18, 2017 at 15:03
"The problem with this solution I need it globally and immediatelly in the class what I want to use" that is not what async/await solves. Nothing can solve that problem. Use callbacks or make everything async. Even if you used async, it still wouldn't be available immediately and globally. — user400654
– user400654, Commented Apr 18, 2017 at 15:11
@PumpkinSeed I didn't downvote you. I rarely downvote people, I attempt to help them - If I ever downvote someone, I comment to let them know why. People who downvote without comment are trolls in my mind. — Kyle Richardson
– Kyle Richardson, Commented Apr 18, 2017 at 15:21
Except your calling function isn't async. async doesn't just magically make asynchronous code run synchronously; it just hides the callbacks behind promises that you then have to add a callback to. It won't and can't solve your design problem. — user400654
– user400654, Commented Apr 18, 2017 at 15:21
FWIW, async functions are part of ES2017, not part of ES6 or ES7. — Felix Kling
– Felix Kling, Commented Apr 18, 2017 at 16:50

thedude · Accepted Answer · 2017-04-19 06:24:35Z

1

The code running the console.log should also be marked as async and it should also await the return value of getFromStorage;

e.g. this would work:

async function waitForStorage() {
   console.log(await getFromStorage());
}
waitForStorage(); // now the console messages should be in the correct order

Or you could just wait for the promise's resolution:

getFromStorage("token").then(someVar => checkToken(someVar))

edited Apr 19, 2017 at 6:24

answered Apr 18, 2017 at 14:52

thedude

9,8371 gold badge34 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

PumpkinSeed Over a year ago

I updated the post, because this isn't really what I'm looking for.

thedude Over a year ago

@PumpkinSeed what you are looking for is not possible unless you mark the scope calling await with async. The simplest solution is just to wait on the promise e.g. getFromStorage("token").then(someVar => checkToken(someVar))

PumpkinSeed Over a year ago

Yes I did it thank you. Can you update the post please?

Jordan Over a year ago

Can we also just do like so? async waitForStorage: () => {}

Collectives™ on Stack Overflow

ES6/7 await for async function

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related