Left right subarray sum product - JavaScript

We are required to write a JavaScript function that takes in an array of numbers of length N (N should be even) and divides the array into two sub-array (left and right) containing N/2 elements each and do the sum of the subarrays and then multiply both the subarrays.

For example: If the input array is −

const arr = [1, 2, 3, 4]

Then the output should be −

(2+1) * (3+4)
= 21

Example

Following is the code −

const arr = [1, 2, 3, 4]
const subArrayProduct = arr => {
   const { length: l } = arr;
   const creds = arr.reduce((acc, val, ind) => {
      let { left, right } = acc;
      if(ind 
Output
Following is the output in the console −
21