CODEWITHSUNDEEP
javascript
Tom Smykowski
Tom Smykowski

Reputation: 26089

How to create a Promise from a variable?

I have a variable:

let x = 1;

What is the simplest way to create a Promise that will right away return the x ? Something like:

let promise = Promise(x);

The question is not about when and how to use Promises. It is clear.

Upvotes: 0

Views: 2866

Answers (2)

Alexander Alexandrov
Alexander Alexandrov

Reputation: 1362

I agree with others Promise.resolve is a straightforward way to wrap a value into Promise. One more option is to use sync and async values inside function:

async function foo<T>(value: T): Promise<T> {
  // do something async
  // and/or return simple value
  return value;
}

const a: Promise<number> = foo(123);
const b: number = await foo(123);

Upvotes: 2

Yoihito
Yoihito

Reputation: 378

You make a resolved promise like this:

let x = 1;
let promise = Promise.resolve(x);

Also you can make a rejected promise:

let rejectedPromise = Promise.reject(x);

Upvotes: 4

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