Stop execution until check is evaluated

Question

How to stop execution until a condition evaluated, this code always return undefined:

function test() {
    var allGood;
    account.isUserAuthenticated().then(function(data) {
        if (data) {
            allGood = false;
        } else {
            allGood =  true;
        }
    });
    return allGood;
}

What do you mean with "stop execution"? This function always returns `undefined` because it does not wait for `isUserAuthenticated` to return (that's why the use of a promise, I think) — Alberto Zaccagni, Jun 02 '16 at 14:58
`function test() { return account.isUserAuthenticated().then(data => !data); }` — Bergi, Jun 02 '16 at 20:27

nem035 · Accepted Answer · 2016-06-02T15:04:48.413

4

You are returning a result that is set inside of an asynchronous call (a promise) which means allGood is first returned (that's why it is undefined) and then sometime later it actually gets a value. What you should do instead is return the promise itself from your function:

function test() {
    return account.isUserAuthenticated().then(function(data) {
        if (data) {
            return false;
        } else {
            return true;
        }
    });
}

Then if you run:

test().then(function(allGood) {
  if (allGood) {
    // user is authenticated
  } else {
    // user is not authenticated
  }
});

edited Jun 02 '16 at 15:04

answered Jun 02 '16 at 14:58

nem035

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1

Also you can use Promise.resolve() instead of return which is easy to understand to someone new in Promises, or at least was easiest for me. – Jose Hermosilla Rodrigo Jun 02 '16 at 15:01
@JoseHermosillaRodrigo: No, you cannot use `Promise.resolve` instead of `return`? I must have misunderstood you there. – Bergi Jun 02 '16 at 20:28
2

@Bergi I have done a fiddle and I realize that Promise.resolve() needs to be returned. https://jsfiddle.net/joherro3/uxdebvyL/1/ – Jose Hermosilla Rodrigo Jun 02 '16 at 21:30

Stop execution until check is evaluated

1 Answers1