map and for...of give different results

Question

I'm trying to iterate through array values in my project.

If I iterate through Array.map() it gives me empty array, but if I iterate with for...of loop I get the right results (new array with values).

const items = await Item.find({ itemId: items.map(item => item) });

for (item of items) {
    itemsArr.push(await Item.find({ itemId: item };
}

This one should help you understand an issue https://stackoverflow.com/a/37576787/11918758 — Nykolai Topchyi, Sep 21 '19 at 20:18
thanks @NykolaiTopchyi i got it now.. i badly used the map function.. — Michal, Sep 21 '19 at 20:35

rawk · Answer 1 · 2019-09-22T04:00:06.637

-2

Array.map is best used when you want to implement a function for every item you loop in

var array1 = [1, 4, 9, 16];

// pass a function to map
const map1 = array1.map(x => x * 2);

console.log(map1);
// expected output: Array [2, 8, 18, 32]

The best case to solve your array.map problem would be

      Promise.all(items.map( async (e) => {
 itemsArr.push(await Item.find({ itemId: e };
}));

edited Sep 22 '19 at 04:00

answered Sep 21 '19 at 20:07

rawk

110
5

1

your map method is not async you need a async map method – joyBlanks Sep 21 '19 at 20:08

map and for...of give different results

1 Answers1