[Algorithm] Search element in a circular sorted array

function findInCircularlySortedAry (ary = [], target) {
  if (ary && ary.length === ) {
    return -;
  }

  if (ary.length === ) {
      return ary[] === target ?  : -;
  }

  let low = ,
      high = ary.length - ;

  while(low <= high) {
    let mid = Math.floor((low + high) / );
    // case 1: target === middle item, return found
    if (ary[mid] === target) {
       return mid;
    }
    // To find which parts (left or right) is sorted
    // case 2: if middle < high, mean from middle to high is sorted
    if (ary[mid] < ary[high]) {
       if (target > ary[mid] && target <= ary[high]) {
           low = mid + ;
       } else {
         high = mid - ;
       }
    }
    // case 3: if low < middle, mean from low to middle is sorted
    else {
      if (target >= ary[low] && target < ary[mid]) {
        high = mid -;
      } else {
        low = mid + ;
      }
    }
  }

  return -;
}

const data = [,,,,,,,];
const res = findInCircularlySortedAry(data,); // 2
console.log(res);

We don't need to