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javascriptpromisees6-promise

How to sort promises in their resolved order not caring about order in arguments

let P1 = new Promise((res, rej) => {
    setTimeout(res("R1"), 2000);
});
let P2 = new Promise((res, rej) => {
    setTimeout(res("R2"), 5000);
});
let P3 = new Promise((res, rej) => {
    setTimeout(res("R3"), 1000);
});

I expect my function to return promises in order they started like this: ["R3", "R1", "R2"]

function preserveOrder([P1, P2, P3]); // should return ["R3, "R1", "R2"]
function preserveOrder([P2, P3, P1]); // should return ["R3, "R1", "R2"]

I can't think of what the best way it is to do this? (since Promise.all() would preserve the order)

Solution

  • You might be looking for

    async function fulfillmentOrder(promises) {
    const results = [];
    await Promise.all(promises.map(promise =>
        promise.then(value => {
            results.push(value);
        })
    ));
    return results;
}