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Checking equality with Promise.resolve vs async return

Sven Snusberg answered on June 7, 2021 Popularity 2/10 Helpfulness 1/10

answer Checking equality with Promise.resolve vs async return

Checking equality with Promise.resolve vs async return

Comment

/* Even though the return value of an async function behaves as if it's wrapped in a
Promise.resolve, they are not equivalent. */

//For example, the following:
async function foo() {
   return 1
}

//...is similar to:
function foo() {
   return Promise.resolve(1)
}

/*An async function will return a different reference, whereas Promise.resolve returns the
same reference if the given value is a promise.*/
const p = new Promise((res, rej) => {
  res(1);
})

async function asyncReturn() {
  return p;
}

function basicReturn() {
  return Promise.resolve(p);
}

console.log(p === basicReturn()); // true
console.log(p === asyncReturn()); // false

Popularity 2/10 Helpfulness 1/10 Language javascript

Source: developer.mozilla.org

Tags: equality javascript return

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