TypeScript for Free: From Basics to Type Design

If you use JS but find it difficult to explain why it works, this course provides the answer. From execution context, closures, and the event loop to Promise concurrency, prototypes, Virtual DOM, memory leaks, and bundle optimization—you won't just read about 18 chapters of advanced JS concepts; you'll learn by seeing them happen right before your eyes with a simulator. Code-based quizzes are provided for every chapter, and you can own it for life for the price of a single chicken dinner.

Have you learned JavaScript but find yourself stuck when it comes to actual projects? I created this course for those who can use forEach but hesitate to use reduce, find asynchronous code a headache every time they see it, and build components without knowing the underlying reasons for their structure. This course doesn't just explain syntax. It focuses on "why we use it this way" to help you develop the coding intuition needed to jump straight into real-world work.

Hello, I am Gamja, a 4th-year frontend developer. Thinking back to when I first learned JavaScript, I remember many times when I felt like I understood everything while following along with YouTube videos or books, but my mind would go completely blank the moment I opened an empty editor. At first, I was just busy copying and pasting code I found through Googling. Because of that, when an error occurred, I didn't know where to start fixing it, and I would spend several days staying up all night in frustration. That’s when I realized a painful truth: writing one line of code yourself while understanding the principles is more valuable for your actual skills than copying someone else's code 100 times. Many beginners struggle with these concerns in front of the high wall of JavaScript: 🚨 "I made the screen look pretty with HTML/CSS, but I feel lost trying to make it move." 🚨 "I've memorized all the syntax for variables and functions, but I don't know how to combine them in practice." 🚨 "My head hurts just hearing terms like event bubbling or DOM manipulation." That is why I prepared this course. I have organized only the 'surest shortcuts' that I learned through countless trials and errors. While preparing the materials, I didn't list difficult development jargon. I boldly discarded the grammar found in thick textbooks that you won't even use right away. Instead, I will plant the core principles used in practice as naturally as breathing into your mind through intuitive everyday metaphors like 'conveyor belts' and 'paint palettes.' In this course, you won't just learn theory. As soon as you learn the theory, you will build four core UIs that you will inevitably encounter in frontend work—such as accordions, tab menus, and dark mode toggles—from scratch with me. After completing the course, you will no longer be someone who scrapes someone else's code and presses the run button while praying. You will be reborn as a real frontend developer who can design how to structure a screen on your own and write JavaScript code according to your intentions. I have included all of my practical know-how. Don't stop in front of an empty editor anymore. It's time to get started.

Are we truly utilizing HTML and CSS to their full potential? Before getting trapped in complex frameworks and JavaScript logic, we will directly implement everything from Whac-A-Mole to escape room games using only markup and styling—the essence of the web. Experience the power of 'fundamentals that aren't swayed by tools,' taught by an active developer with 4 years of experience.

This is an introductory course where you will learn the core syntax of TypeScript to improve type safety and code readability through hands-on practice. You will learn everything from project environment setup to interfaces, generics, and utility types using real-world code examples.

This is a course for those starting with TypeScript. The curriculum has been designed so that even those unfamiliar with modern JavaScript syntax can learn easily. Let's learn TypeScript, which may seem difficult, in an easy and fun way from a beginner's perspective 😄

In this course, you will learn about TypeScript.

This is the practical application section of "Introduction to TypeScript - From Basics to Practice". If you haven't taken the introductory course, please start with the introductory section first 😄

This is an all-in-one course that takes you from the basics of TypeScript-based Next.js 16+ to a production-ready project level. You will learn by directly implementing core concepts and practical patterns of the latest Next.js, including App Router, Server Components, Server Actions, Caching, Cache Components, authentication, performance optimization, and deployment.

This course is about TypeScript and React.

This is a project-oriented course where you will build a "ToDo List" app using React and TypeScript with a professional touch. Beyond simply learning syntax, you will gain practical experience in using TypeScript by completing a real-world service—from component structure design and state management to type application, feature implementation, local storage integration, and deployment.

Now it's time to take on a real-world challenge 🔥 We will develop a production-grade SNS using React.js + TypeScript + Supabase, building features such as authentication & authorization, infinite scroll, image uploads, likes, infinitely nested comments, and dark mode. In the process, we will also explore server and global state management techniques using Zustand and Tanstack Query.

You will learn about what a node is, the latest JavaScript grammar, the node API, npm, the module system, databases, testing, and more. You will create a project using five practical examples. You will also deploy a service to the cloud and convert a node project to TypeScript.

I recommend this to those who want to learn how to easily create and distribute Android apps, Windows apps, and iOS apps. We will teach you the basics of TypeScript rather than JavaScript and Angular!

JavaScript, TypeScript Next is backend development! You will be able to develop REST API backends using NestJS, develop and deploy Socket IO.

Completing an integration project between an API server built with Spring Boot (ver 3.4.x) and React 19 (with TypeScript)! Applying front-end to a back-end portfolio! A course written for working professionals (not a beginner-level course).

A course to learn the latest Node.js backend REST API using fastify, a Node.js framework boasting high speed, ORM Prisma, and Typescript.

We will develop an avatar-based community app using React Native. You will learn the process of creating a high-quality community app that includes not only post creation but also comments/replies, likes, polls, and avatar generation.

"Why did the AI write this code?" or "Why can't it remember what I just said?" The frustration you encounter when using AI tools like Claude Code stems from not knowing how the tool actually works. This course flings open that black box. Over 25 lessons, we will build our own Coding Agent from scratch that functions exactly like real-world professional tools—giving the LLM 'eyes' to see files (Read), 'hands' to fix code (Edit), and 'feet' to execute commands (Bash). This isn't just about learning how to use a library. You will gain hands-on experience by implementing code to understand how AI perceives project structures, why it loses its memory during long conversations, and how to solve those issues technically (Sliding Window, Summary). Through this process, you will evolve from being a mere 'user' of AI tools to an 'AI provider' who understands the underlying principles and can customize and evaluate tools to fit your specific needs.

In this course, you will be able to create a Reddit website from scratch, step by step.

Learn Springboot + NextJS RestAPI Board Creation Faster Than Anyone! Develop a CRUD server with Springboot and create your own board with NextJS!

This course is a practical, hands-on guide for those who want to learn how to maximize development productivity in the AI era. Beyond simply learning how to use AI, we focus on how to utilize Claude Code in a real-world development environment and how to produce "proper results." Many developers use AI but still face issues such as: ❌ Inconsistent results ❌ Poor code quality ❌ Increasing project complexity To solve these problems, this course teaches you how to utilize AI as a "development partner" rather than just a tool through: ✔ Spec-based workflows ✔ Structured command systems ✔ Sub-agent and automation strategies Furthermore, you will gain the experience of completing and deploying a full application from start to finish by integrating with real-world services such as Firebase, Figma, GitHub, and Vercel.