Function to nesting comments in typescript

nestingComments.ts

/**
 * Examples :
 * [
 *   { id: 1, text: 'Hello', replyToId: null, },
 *   { id: 2, text: 'Hi', replyToId: 1, },
 *   { id: 3, text: 'Hello World', replyToId: 2, },
 * ]
 * 
 * ======== TO ========
 *
 * [
 *  { 
 *    id: 1, 
 *    text: 'Hello', 
 *    replyToId: null, 
 *    replies: [
 *      { 
 *        id: 2, 
 *        text: 'Hi', 
 *        replyToId: 1, 
 *        replies: [
 *          {
 *            id: 3,
 *            text: 'Hello World',
 *            replyToId: 2,
 *          }
 *        ]
 *      }
 *    ]
 *  },
 * ]
 */

type TComment =  {
  id: number;
  text: string;
  replyToId: TComment["id"] | null;
  replies?: TComment[];
}

/**
 * Nesting comments
 * @param comments TComment
 * @returns TComment[]
 */
function nest<T extends TComment> (comments: T[]) {
  if (comments.length === 0) {
    return comments
  };

  return comments.reduce<T[]>((nested, comment) => {
    comment.replies = comments.filter(
      reply => reply.replyToId === comment.id
    );

    nest(comment.replies);

    if (comment.replyToId == null) {
      nested.push(comment);
    }

    return nested
  }, []);
};