Gotchas

map

map with async function
Result is promises
Resolve promises using Promise.all
Result is proper objects

SUGGESTION -- Use js traditional code style with promises (async and await). Keep it simple. Do NOT use functional programming style -- there are gotchas (with fp) as shown here.

let a, b;
a = [10, 20, 30, 40];
1b = a.map(async n => await n / 10);
console.log(b);
//Map gives us promises:
2//[ Promise { 1 }, Promise { 2 }, Promise { 3 }, Promise { 4 } ]

//Resolve promises
3b = await Promise.all(b);
console.log(b);
//Now we have proper objects
4//[ 1, 2, 3, 4 ]

reduce

reduce with async function
Result is a promise
Resolve promises using Promise.all
Result is objects but still a bit of a promise -- see warnings above and below

SUGGESTION -- Use js traditional code style with promises (async and await). Keep it simple. Do NOT use functional programming style -- there are gotchas (with fp) as shown here.

let a, promise;
a = [10, 20, 30, 40];
1promise = a.reduce(async (accum, each) => await (accum + each));
console.log(promise);
//Map gives us promises:
2//Promise { <pending> }

let resolvedValue;
3resolvedValue = await promise;
console.log(resolvedValue);
//Map gives us promises:
4//[object Promise]40