Binary Search

function binarySearch(arr, n, start = 0, end = arr.length) {
    let mid = Math.floor((end + start) / 2);
    if (arr[mid] === n) return mid;

    if (start < end - 1) {
        if (n > arr[mid]) {
            return binarySearch(arr, n, mid, end);
        } else {
            return binarySearch(arr, n, start, mid);
        }
    }
    return -1;
}