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Oct 23, 2023 · A promise may do three things with the shared state: make ready: the promise stores the result or the exception in the shared state. Marks the state ready and unblocks any thread waiting on a future associated with the shared state. release: the promise gives up its reference to the shared state. If this was the last such reference, the shared ...
Feb 9, 2018 · Async functions wrap their returned result in a Promise, and if you want the actual value which the promise resolved to, you have to use await someAsyncFunc(). Put in a simple example: return 1; console.log(asyncCall()); // this doesn't wait for the Promise to resolve. console.log(await asyncCall()); // this does.
Aug 17, 2016 · 156. In C#: Task<T> is a future (or Task for a unit-returning future). TaskCompletionSource<T> is a promise. So your code would translate as such: // var promise = new Promise<MyResult>; var promise = new TaskCompletionSource<MyResult>();
Feb 4, 2018 · The promise resolution procedure is an abstract operation taking as input a promise and a value, which we denote as [[Resolve]](promise, x). If x is a thenable, it attempts to make promise adopt the state of x, under the assumption that x behaves at least somewhat like a promise. Otherwise, it fulfills promise with the value x.
Jul 27, 2017 · Considering that promise asynchronous code can be handled with async..await, current use case for Promise constructor is non-promise asynchronous code, e.g.: new Promise(resolve => setTimeout(resolve, 1000)) When Promise constructor contains synchronous code or involves other promises, a promise should be constructed with async function.
May 14, 2015 · A promise is not a control surface for the async action fulfilling it; confuses owner with consumer. Instead, create asynchronous functions that can be cancelled through some passed-in token. Another promise makes a fine token, making cancel easy to implement with Promise.race: Example: Use Promise.race to cancel the effect of a previous chain:
Sep 14, 2019 · 7. Actually it depends on your node version, But if you can use async/await then your code will be more readable and easier to maintain. When you define a function as 'async' then it returns a native Promise, and when you call it using await it executes Promise.then.
Jan 2, 2015 · To see if the given object is a ES6 Promise, we can make use of this predicate: return p && Object.prototype.toString.call(p) === "[object Promise]"; Call ing toString directly from the Object.prototype returns a native string representation of the given object type which is "[object Promise]" in our case.
Accessing the value of promiseB is done in the same way we accessed the result of promiseA. promiseB.then(function(result) {. // here you can use the result of promiseB. }); As of ECMAScript 2016 (ES7, 2016), async / await is standard in JavaScript, which allows an alternative syntax to the approach described above.
Dec 2, 2017 · You're partially right. It's because you're trying to get the result of this asynchronous call in a synchronous fashion. The only way to do this is the same way you deal with any other promise. Via a .then callback. So for your snippet:
