This content originally appeared on DEV Community and was authored by Suprabha
FlatMap is a single method which can be usable for flat and map methods.
As you know flat(), flattening the 1-level deep and map() to loop into an array.
If we include both, we called flatMap() ?
So, instead if calling two methods flat() and map(), you can use single method called flatMap().
let plants = ['?', '?', '?', '?'];
// ❌ map + flat
plants.map(plant => [plant, '?']).flat();
// Output
//["?", "?", "?", "?", "?", "?", "?", "?"]
// ✅ flatMap
plants.flatMap(plant => [plant, "?"])
// Output
// ["?", "?", "?", "?", "?", "?", "?", "?"]
How flatMap() works?
? FlatMap() always do first map() and then it flat().
In flat(), we use to pass arguments where you set the depth, arguments define how deep a nested array should be flattened.
let plants = [[["?", "?"]]];
plants.flat(2);
// ["?", "?"]
flatMap() do only 1 level deep flattening.
let plants = [[["?", "?"]]];
plants.flatMap(plant => [plant]);
// [["?", "?"]]
Filter using flatMap ?
Yes, You can also do filter here using flatMap().
let arr = [5, 4, -3, 20, -4, 18]
arr.flatMap(i => {
return i < 0 ? [] : [i];
})
// [5, 4, 20, 18]
Reference ?
Summary ∑
flatMap() method always helps if you want to use map and flat methods both together.
Thanks for reading the article ❤️
| ??? suprabha.me |
This content originally appeared on DEV Community and was authored by Suprabha
Suprabha | Sciencx (2021-07-24T20:12:52+00:00) Array FlatMap. Retrieved from https://www.scien.cx/2021/07/24/array-flatmap/
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