Is there a one-line code to get an subarray from an array by index?
For example, suppose I want to get ["a","c","e"] from ["a","b","c","d","e"] by [0,2,4]. How to do this with a one-line code? Something like ["a","b","c","d","e"][0,2,4]..
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4 Answers
You could use map;
var array1 = ["a","b","c"];
var array2 = [0,2];
var array3 = array2.map(i => array1[i]);
console.log(array3);
2 Comments
klugjo
I actually like this better than my answer. Probably faster as well.
Carlos Delgado
Is there a way so you don't have to traverse the array? Like a direct extraction from indexes or something like that?
You can use filter
const arr = ['a', 'b', 'c'];
const indexes = [0, 2];
const result = arr.filter((elt, i) => indexes.indexOf(i) > -1);
document.body.innerHTML = result;6 Comments
klugjo
What do you mean ?
Alexis
@NinaScholz OP doesn't ask for this
Muhammet Can TONBUL
const indexes = [2, 2]; try this @klugjo
Cerbrus
@MuhammetCanTONBUL: That's pretty silly input considering what the OP is trying to do.
klugjo
It does work, it returns ['c'], which is what we want I am guessing. Question doesn't say
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You can use a combination of Array#filter and Array#includes
const array = ['a','b','c'];
console.log(array.filter((x,i) => [0,2].includes(i)));4 Comments
Cerbrus
Nice and simple. Although I'd have used a variable for the indexes array.
Weedoze
@Cerbrus I first wrote it with a variable but then I thought it was more visual to have it inline
Cerbrus
Fair enough :-) Either way, +1
Weedoze
@Cerbrus Thanks for your comment ! Always nice to receive compliment :-D
You can use Array.prototype.reduce()
const arr = ['a', 'b', 'c', 'd', 'e'];
const indexes = [0, 2, 4];
const result = indexes.reduce((a, b)=> {
a.push(arr[b]);
return a;
}, []);
console.log(result);
