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Tertiumnon — Sat, 07 Jun 2025 05:17:44 +0000

Cooking with TypeScript enums

Tertiumnon — Wed, 26 Mar 2025 16:42:35 +0000

Periodically I hear that something wrong with TypeScript enums. But if you understand how it works - it's not an issue for you.

The usage is very simple:

enum Role {
  None = 0,
  Moderator = 1,
  Admin = 2,
}

And we have a good news here - we can use string values in TypeScript! For instance, C# enums can't work with string values.

enum UserRole {
  None = "",
  Moderator = "moderator",
  Admin = "admin",
}

Pros and cons of enums

Excessive JavaScript code after compilation

I think the claim that TypeScript enums produce excessive JavaScript code is somewhat overstated. Have you ever wondered how much code your compiler generates? I highly doubt it. But when it comes to types, you somehow think differently. Don't you find that strange?

Let's take a look on generated JS code.

var Role;
(function (Role) {
    Role[Role["None"] = 0] = "None";
    Role[Role["Moderator"] = 1] = "Moderator";
    Role[Role["Admin"] = 2] = "Admin";
})(Role || (exports.Role = Role = {}));

Looks ugly but it doesn't produce any "terrible" effects.

We can continue our investigation. Let's create a file with enum and a file with type.

export type RoleType = "" | "moderator" | "admin";

And than we can import both files to apply values from both kinds.

import { UserRole } from './enum';
import { RoleType } from './type';

const role = UserRole.Moderator;
const roleType: RoleType = "moderator";

The result in JS will be:

var enum_1 = require("./enum");

var role = enum_1.UserRole.Moderator;
var roleType = "moderator";

You see here that enum produce a variable with values but type don't. It means that enum don't repeat itself. It's an Object with properties.

Let's create a class - another TypeScript feature.

export class User {
  name: string;
  email: string;
}

And you will get the next compiled JS code:

var User = /** @class */ (function () {
    function User() {
    }
    return User;
}());

Looks ugly too, isn't it? More code, more problems? I don't think so!

I worked with many projects and teams, and you should know that very common problems are:

Over-complicated code (ignoring all principles of clean coding)
Inefficient code (CPU and memory loading)
Environment issues (caching invalidation, network loading, etc.)
Legacy dependencies (security issues, difficulties with upgrading)

Non-obviousness of usage

The most common example of incorrect use of enums is shown in the code below.

enum UserRole {
  Admin,
  Moderator,
}

And this is a real problem here. Problem for those who don't understand some JS and TS nuances.

// you will get a logically incorrect result
const ROLES_VALUES = Object.values(UserRole); // ["Admin", "Moderator", 0, 1]

This is the reason why we always must use values for enums.

A good part of `enums`

Enums can help you create arrays and objects that we might need in other parts of the project.

const isRoleValueCorrect = (value: UserRole) => ROLE_VALUES.includes(value);

Or you can create options for select:

const options = Object.entries(UserRole).map(arr => ({label: arr[0], value: arr[1]}));
/*
[{
  "label": "None",
  "value": ""
}, {
  "label": "Moderator",
  "value": "moderator"
}, {
  "label": "Admin",
  "value": "admin"
}] 
 */

Conclusions

TypeScript enums is not a "bad" feature.

In some case it's confusing but only if you don't understand how to work with that.

This is convenient if you want to create related data structures.

A minimum of books that should be read by a novice or experienced programmer

Tertiumnon — Wed, 26 Mar 2025 12:57:17 +0000

Below a small list of books that I can personally recommend for reading to all programmers, including beginners. As it usually happens that I bought, I sell it.

Computer Science fundamentals

Computer Science Distilled (Wladston Ferreira Filho)

This is an super-"based" book which is well-suited for beginners, particularly for those who have no specialized education.

Harvard CS50 video course

This is not a book, but perhaps the best that you can find for training a base. This is a magnificent Harvard course, on the example of which you will understand why people seek to get to study in places such as Harvard. You can watch this course online absolutely free.

Also, you can earn a certificate on edx.org or on the Harvard website. The course is regularly updated, so if you started, it is better to finish in the same year.

Programming

Object-Oriented Thought Process (Matt Weisfeld)

I would describe this book as the initial one for those who want to use the OOP in their work. I know that this book is not very popular, but it personally helped me in due time to "set up" some concepts in my head.

Head First Design Patterns (Eric Freeman, Elisabeth Robson, Bert Bates, Kathy Sierra)

There are two versions of these books - one of them contains illustrations for better understanding. Understanding the patterns will allow you to structure various approaches in your head and communicate in the same language with other programmers, choosing solutions for certain problems.

Clean Code (Robert Martin)

In the book you will find a set of rules that will help you write understandable for yourself and, which is much more important in large companies, a code understood for other programmers. The sooner you read this book, the better.

Test Driven Development: By Example (Kent Beck)

Sometimes programmers neglect testing (which is bad). The book will inspire you to write tests, or at least give food for thought.

Algorithms and data structures

Grokking Algorithms (Aditya Y. Bhargava)

The book gives basic ideas about the algorithms and data structures. The book is loved by many for its simplicity, with which the author explains key principles. If you read, understand and implement everything that is in this book, then you should not have problems with the next book. It is recommended to read the updated (fixed) version of the book.

Cracking the Coding Interview (Gayle Laakmann McDowell)

Essentially, this book is intended for those who are going through interviews at major technology companies. A lot of material is dedicated to the main section – algorithmic.

System Design

System Design (Alex Xu)

A well-structured book that is often recommended for reading before undergoing interviews. Numerous diagrams, describing various 'IT-related' things, by the same author can be found online.

High Load

Designing Data-Intensive Applications (Martin Kleppmann)

Famous "book with the boar", one of the fundamental books for a programmer who wants to proudly call themselves a Software Engineer.

Management

Software Engineering at Google (Titus Winters, Tom Manshreck, Hyrum Wright)

The book provides general insights into development at tech giants like Google. You can learn how to be a good manager, hire engineers and evaluate their performance, test, scale, and decide on tools to use – a lot of useful content.

Agile Estimating and Planning (Mike Cohn)

In my opinion, the book is somewhat verbose. However, it contains very detailed descriptions of team interactions working with Agile methodology, which you'll start to understand and use better.

Afterword

It would be interesting to see your minimum set of books in the comments. If there are any remarks, I'll try to improve the article or publish an updated version later.

You don't need Redux

Tertiumnon — Wed, 12 Mar 2025 11:11:55 +0000

As you're likely aware, Dan Abramov published a post titled "You Might Not Need Redux" back in 2016. Yet, here we are in 2025, and it appears that many projects and job postings haven't adapted. Sadly, not much has changed.

The Yandex expert in the video below demonstrates that you can thrive without using Redux.

Please, be aware the video contains Russian language and auto-generated English subtitles.