Javascript object oriented programming help

Javascript object oriented programming help

I am solving this Javascript Object oriented programme homework with the instructions below.

Object Oriented Tests

For this challenge, you are going to build a mock comments section.


We’re going to focus on two aspects:


  • Users come in 3 flavors, normal users, moderators, and admins. Normal users can only create new comments, and edit the their own comments. Moderators have the added ability to delete comments (to remove trolls), while admins have the ability to edit or delete any comment.
  • Users can log in and out, and we track when they last logged in


  • Comments are simply a message, a timestamp, and the author.
  • Comments can also be a reply, so we’ll store what the parent comment was.

Your Challenge

This is challenge is not about building a fully functional API, but more about focusing on the design from an object-oriented point-of-view.

We’ve provided the basic API (which is incomplete), which we would like you to complete being aware of the following Object-Oriented Programming concepts:

Encapsulation of Properties

All classes should have no publicly accessible fields

You should make sure you at least “hide” the required fields, for example, using _name instead of _name. Alternatively, feel free to use a better solution as extra credit.

The method-based API is provided. These must be completed as-is.

Additional methods are allowed, though remember to keep read-only properties read-only.


  • Classes should be instantiated with properties (as provided), to create instances with values already assigned.
  • User/Moderator/Admin defaults:
    • Should be marked as not logged in
    • Should return null for the last logged in at property
  • Comment defaults:
    • Should set the current timestamp for the created at property upon instantiation
    • Replied To is optional, and should be null if not provided.

Inheritance & Access Control

Note: for the sake of simplicity, you can simply treat object equality as “equal”, though more complete solutions will also pass.

  • User
    • Users can be logged in and out.
    • When logging in, set the lastLoggedInAt timestamp. Do not modify this timestamp when logging out
    • Users can only edit their own comments
    • Users cannot delete any comments
  • Moderator is a User
    • Moderators can only edit their own comments
    • Moderators can delete any comments
  • Admin is both a User and a Moderator
    • Admins can edit any comments
    • Admins can delete any comments


  • Comments contain a reference to the User who created it (author)
  • Comments optionally contain a reference to another comment (repliedTo)
  • When converting to a string (toString), the following format is used:
    • No replied to:

message + " by " +

  • With replied to:

message + " by " + + " (replied to " + + “)”

Beyond these basics, you are free to add to the API, but only these concepts will be scored automatically.


  • Using ES6-style classes

  • See below for an alternative ES5-prototype solution setup


`class User {

constructor(name) {}

isLoggedIn() {}

getLastLoggedInAt() {}

logIn() {}

logOut() {}

getName() {}

setName(name) {}

canEdit(comment) {}

canDelete(comment) {}


class Moderator {}

class Admin {}

class Comment {

constructor(author, message, repliedTo) {}

getMessage() {}

setMessage(message) {}

getCreatedAt() {}

getAuthor() {}

getRepliedTo() {}

toString() {}



  • Alternative using ES5 prototypes

  • Or feel free to choose your own solution format

function User(name) {}

User.prototype = {

isLoggedIn: function() {}

getLastLoggedInAt: function() {}

logIn: function() {}

logOut: function() {}

getName: function() {}

setName: function(name) {}

canEdit: function(comment) {}

canDelete: function(comment) {}


var Admin = ???

var Moderator = ???

function Comment(author, message, repliedTo) {}

Comment.prototype = {

getMessage: function() {}

setMessage: function(message) {}

getCreatedAt: function() {}

getAuthor: function() {}

getRepliedTo: function() {}

toString: function() {}


Can somebody who is sound in Javascript object oriented programming who can understand this question to solve it for me with step by step explanation and code adhereing to the specified instructions. I will be glad to get the answer and explation. It looks like my solution is not complete as it is not passing all the test. Please help…

See what I have tried below.

getString(comment) { const authorName = comment.getAuthor().getName(); if (!comment.getRepliedTo()) return authorName; return${comment.getMessage()} by ${authorName} (replied to ${this.getString(comment.getRepliedTo())}); } toString() { if(!this._repliedTo){ return${this._message} by ${this._author.getName()}; } else { return${this._message} by ${this._author.getName()} (replied to ${this._repliedTo.getAuthor().getName()})} }