rtt-modal-next-focus.tsx

export const nextFocusable = (elements: HTMLElement[], forward = true) => {
  const currentIndex = elements.findIndex((e) => e === document.activeElement);
  let nextIndex = 0;

  if (currentIndex > -1) {
    if (forward) {
      nextIndex = currentIndex < elements.length - 1 ? currentIndex + 1 : 0;
    } else {
      nextIndex = currentIndex > 0 ? currentIndex - 1 : elements.length - 1;
    }
  }

  elements[nextIndex]?.focus();
};