Alternating Sum

You are given an array of positive integers - the weights of the people. Return an array of two integers, where the first element is the total weight of team 1, and the second element is the total weight of team 2 after the division is complete.

Example
console.log(alternatingSums([50, 60, 60, 45, 70])) [180, 105]
even: 60 + 60 + 50 = 170
odd: 45 + 70 = 105

function alternatingSums(a) {
  let evenSum = 0;
  let oddSum = 0;

  a.forEach((element,index) => {
    if (index % 2 === 0) {
      evenSum += element;
    }else {
      oddSum += element
    }
  })

  return [evenSum,oddSum]
}

console.log(alternatingSums([50, 60, 60, 45, 70])) [180, 105]

We create function called alternatingSums with parameter a and local variable evenSum = 0 and oddSum = 0

We loop the array given into the parameter a with forEach loop that takes arguments element and index

Inside the forEach loop we check if index % 2 === 0 than we eventSum += element else oddSum += element

The forEach() method executes a provided function once for each array element. - MDN

So if all the cases above are false we return [eventSum, oddSum