```
/**The index of target in a sorted array, or -1 if target is not found. */
export function binarySearch(items: readonly number[], target: number): number {
  if (items.length === 0) return -1;

  let low = 0;
  let high = items.length - 1;

  while (low <= high) {
    const mid = Math.floor((low + high) / 2);

    if (items[mid] < target) {
      low = mid + 1;
    } else if (items[mid] > target) {
      high = mid - 1;
    } else {
      return mid; // Found the target, return its index
    }
  }

  return -1; // Target not found
}
```