Add and Subtract

function addAndSubtract(arr) {
    let sumOldArray = 0;
    let sumNewArray = 0;
    let evenNum = 0;
    let oddNum = 0;
    let newArray = [];
    for (let i = 0; i < arr.length; i++) {
        sumOldArray += arr[i];

        if (arr[i] % 2 === 0) {
            evenNum = arr[i] + i;
            newArray.push(evenNum)
        } else {
            oddNum = arr[i] - i;
            newArray.push(oddNum);
        }
    }
    for (let i = 0; i < newArray.length; i++) {
        sumNewArray += newArray[i];
    }
    console.log(newArray);
    console.log(sumOldArray);
    console.log(sumNewArray);
}