Below is the code, I want to return the sum of all the array elements, why is it not working. I know we don't need the Promise to achieve that but I would like to know how it can be done with a Promise.
const arr = [1, 5, 7, 8];
function sumPromise(a, b) {
return new Promise((res) => {
setTimeout(() => {
res(a + b);
}, 1000);
});
}
let res = arr.reduce(sumPromise);
res.then((a) => console.log(a));
output:[object Promise]8
I hope this will help
const arr = [1, 5, 7, 8];
function sumPromise(a, b) {
return new Promise((res) => {
setTimeout(() => {
a.then(item => res(item + b))
}, 1000);
});
}
let res = arr.reduce(sumPromise, Promise.resolve(0));
res.then((a) => console.log(a));Without changing sumPromise
const arr = [1, 5, 7, 8];
function sumPromise(a, b) {
return new Promise((res) => {
setTimeout(() => {
res(a + b);
}, 1000);
});
}
let res = arr.reduce(
(a, b) => a.then(item => sumPromise(item, b)),
Promise.resolve(0)
);
res.then(console.log);let total = 0;
const arr = [1, 5, 7, 8];
function sumPromise(a, b) {
return new Promise((res) => {
setTimeout(() => {
res(total = total + b);
}, 1000);
});
}
let res = arr.reduce(sumPromise, total);
res.then((a) => console.log(total));