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Reduce an array to the sum of every nth element - JavaScript
We are required to write a JavaScript function that takes in an array of numbers and returns the cumulative sum of every number present at the index that is a multiple of n from the array.
Let’s write the code for this function −
const arr = [1, 4, 5, 3, 5, 6, 12, 5, 65, 3, 2, 65, 9];
const num = 2;
const nthSum = (arr, num) => {
let sum = 0;
for(let i = 0; i < arr.length; i++){
if(i % num !== 0){
continue;
};
sum += arr[i];
};
return sum;
};
console.log(nthSum(arr, num));Output
Following is the output in the console −
99
Above, we added every 2nd element beginning with index 0 i.e.
1+5+5+12+65+2+9 = 99
Updated on: 14-Sep-2020
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