react-hook-form/src/utils/move.ts

import isUndefined from './isUndefined';

export default <T>(
  data: (T | undefined)[],
  from: number,
  to: number,
): (T | undefined)[] => {
  if (!Array.isArray(data)) {
    return [];
  }

  if (isUndefined(data[to])) {
    data[to] = undefined;
  }
  data.splice(to, 0, data.splice(from, 1)[0]);

  return data;
};