Using conditional map function to transform array

Question

I have an array of numbers, that I want to map into a new array of numbers.

let numbers= [1,3,5,10,11]

needs to be turned into

var result = [4,8,15,21,11];

i tried using ES6 shorthand syntax, to do it. But there is not really any coherence between the numbers, so i though a callback would be better

let numbers= [1,3,5,10,11]

const result = numbers.map(x => resultBinding(x))


function resultBinding(x){

}

now my issue here is that I don't want to try to avoid making a lot of if-statements to determinate each value.

This was an assignment, given y my teachers, there is no real logic behind it. I also think this is a strange task, since this has little relevance to an actual project.. — Kristoffer Tølbøll
– Kristoffer Tølbøll, Commented Dec 22, 2018 at 14:12

Jonas Wilms · Accepted Answer · 2018-12-22 14:20:33Z

4

I'd use reduce to keep track of the previous array value using the accumulator:

 const result = [];
 array.reduce((a, b) => (result.push(a + b), b));
 result.push(array.pop()); // add the trailing 11

answered Dec 22, 2018 at 14:20

Jonas Wilms

139k20 gold badges164 silver badges164 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Ori Drori · Accepted Answer · 2018-12-22 14:24:15Z

3

Iterate it with Array.map(). Combine the current item, and the next item (or 0 if undefined):

const numbers= [1,3,5,10,11]

const result = numbers.map((n, i) => n + (numbers[i + 1] || 0));
  
console.log(result);

edited Dec 22, 2018 at 14:24

answered Dec 22, 2018 at 14:12

Ori Drori

196k32 gold badges243 silver badges233 bronze badges

Comments

iambinodstha · Accepted Answer · 2018-12-22 16:02:01Z

3

operation of result = [1+3, 3+5, 5+10, 10+11, 11]. last index of result is same as numbers array because there is no index after that.

let numbers= [1,3,5,10,11];

let result = numbers.map((num, index)=> (index+1) >= numbers.length ? num : num + numbers[index+1])

console.log(result);

answered Dec 22, 2018 at 16:02

iambinodstha

1,00711 silver badges12 bronze badges

Collectives™ on Stack Overflow

Using conditional map function to transform array

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related