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Javascript – Is there a meaningful difference between an async IIFE and a new Promise?

Consider the following assignments:

const promise1 = (async () => {
    await someAsyncFunction();
})();

const promise2 = new Promise(async resolve => {
    await someAsyncFunction();
    resolve();
});

Is there any meaningful difference between these two Promises (other than verbosity)?

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2

Answers


  1. Chosen as BEST ANSWER
    0

    Consider the following definition of someAsyncFunction:

    async function someAsyncFunction() {
    throw "Error in someAsyncFunction!";
}

    In this case, both promise 1 and promise 2 cause an unhandled rejection error. But afterwards, the two promises are in different states. Promise 1 (defined using the async IIFE) has rejected with the reason "Error in someAsyncFunction!" but promise 2 is still pending. This behavior was confirmed in NodeJS and Firefox.


  2. 0

    They’re basically the same, the IIFE is syntactic sugar for the 2nd version

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