Javascript - . map()

Question

Good morning guys, I have an array, however I only want to multiply the array index 2 using .map(). Below is an example where I am multiplying all array positions.

const nums = [1,2,3,4,5]

let result = nums.map(function(e, i, arr) {
    return e * 2 
})
console.log(result)

How to modify position 2 only?

Answer 1

If you just want to modify the Indice 2 just do so:

nums[2] = nums * 2;

So you change the internal value of the array without needing to reassign. If you want to use .map() which is the best solution you can often do so:

let result = nums.map(function(e, i, arr) {
    return i === 2 ? e * 2 : e; 
})