comments-to-tree v1.0.0

What is this for?

A micro utility that converts a one-dimensional array with comments into a comments tree.

API

// We need the comments come from a database with such properties, at least.
interface DefaultCommentFromDb
{
  commentId: number | string;
  parentId?: number | string;
}

// This utility will convert comments from the database to comments with this interface.
interface DefaultComment
{
  commentId: number | string;
  children: this[];
  parentId?: number | string;
  parent?: this;
}

This utility has one public method:

static getTree<T extends DefaultCommentFromDb, U extends DefaultComment>
(
  allCommentsFromDb: T[],
  actionRoot: 'unshift' | 'push',
  actionChild: 'unshift' | 'push'
): U[];

Please do not be afraid =). It's easy to use this method.

CommentsToTree.getTree() - converts a one-dimensional array of comments into a comments tree. The array must be sorted in reverse order - at its beginning there are the most recent comments.

allCommentsFromDb - one-dimensional array of comments from the database (the array sorted in reverse order).

actionRoot - the action you need to apply to insert a root comment. By default unshift.

actionChild - the action you need to apply to insert a child comment. By default unshift.

Install

npm install comments-to-tree --save

Usage

First of all, you need to extends the defaults interfaces. After that, you need extends DefaultCommentsToTree to override the protected method transform():

import { DefaultCommentsToTree, DefaultCommentFromDb, DefaultComment } from 'comments-to-tree';


interface CommentFromDb extends DefaultCommentFromDb
{
  // Additional property from database.
  someOtherPropertyFromDb: string;
}

interface Comment extends DefaultComment
{
  // Additional transformed property.
  someOtherProperty: string;
}

class CommentsToTree extends DefaultCommentsToTree
{
  protected static transform(allCommentsFromDb: CommentFromDb[]): Comment[]
  {
    return allCommentsFromDb.map(commentFromDb =>
    {
      return {
        commentId: commentFromDb.commentId,
        parentId: commentFromDb.parentId || 0,
        children: [],
        // Additional property.
        someOtherProperty: commentFromDb.someOtherPropertyFromDb
      };
    });
  }
}

const allCommentsFromDb: CommentFromDb[] =
[
  {commentId: 5, parentId: 2, someOtherPropertyFromDb: 'comment5'},
  {commentId: 4, someOtherPropertyFromDb: 'root comment4'},
  {commentId: 3, parentId: 1, someOtherPropertyFromDb: 'comment3'},
  {commentId: 2, parentId: 1, someOtherPropertyFromDb: 'comment2'},
  {commentId: 1, someOtherPropertyFromDb: 'root comment1'},
];

const commentsTree = CommentsToTree.getTree<CommentFromDb, Comment>(allCommentsFromDb);