next/src/utils/helpers.ts

type Constructor<T> = new (...args: unknown[]) => T;

/* Check whether array is of the specified type */
export const isArrayOfType = <T>(
  arr: unknown[] | unknown,
  type: Constructor<T> | string
): arr is T[] => {
  return (
    Array.isArray(arr) &&
    arr.every((item): item is T => {
      if (typeof type === "string") {
        return typeof item === type;
      } else {
        return item instanceof type;
      }
    })
  );
};