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Building a Node.js Server Engine – Learning Framework Design through an Express.js Clone

Beyond simply using Express.js, this lecture will have you directly implementing its internal engine from scratch to finish, allowing you to truly internalize the operating principles of a real server. You will directly build all of Express's components, such as routers, middleware, request-response objects, static file handling, and template rendering, from the ground up, providing an experience that fosters growth as a server developer.

(4.0) 1 reviews

17 learners

  • nhcodingstudio
실습 중심
백엔드이해하기
express.js클론
node.js백엔드
웹서버프레임워크구현
JavaScript
Node.js
Express
backend
software-design

What you will learn!

  • How to understand the core principles of web server architecture from the ground up by implementing Express.js

  • How to perfectly grasp Express.js's core principles by implementing its entire architecture.

  • How middleware chains and the next() function pass requests and continue the control flow

  • Structurally analyze how request (req) and response (res) objects are actually composed and transmitted.

  • Secure static file server implementation

  • Implement stream-based logic that directly parses JSON and URL-Encoded request bodies

  • How to build a complete CRUD API by directly designing a RESTful router

  • Modular router setup connected to main app, like `express.Router()`.

  • Rendering dynamic HTML by integrating EJS

  • Implementing a structure for safe sync/async error handling in middleware chains.

  • How to verify full server functionality and perform integration testing through automated API test scripts

🚀 From “User” to “Implementer” – Learn Core Principles of Server Development by Cloning Express.js

This course will take you on a journey to clone the engine of Express.js, the most widely used server framework in the web ecosystem, and implement its inner workings.

I remember when I first learned Node.js and Express . I was really impressed by how easy it was to implement routing, middleware, static file processing, and template rendering with just one line of methods like app.get() or app.use() . But at some point, the question arose, Am I someone who can create this, or am I someone who simply uses it?

Express is a very convenient tool, but its internal structure is hidden, so it is often difficult to understand how it works. This course was created to relieve that thirst.

How is the routing system designed, why is middleware executed in order, how is the MIME type of static files set? The process of finding answers to all these questions through hands-on implementation and practice is the core of this lecture.

By implementing Express yourself, you will gain a fundamental sense of server development that goes beyond just knowing Express and will allow you to naturally understand the structure of other frameworks such as Fastify, Flask, Django, and Spring Boot .

Let's start the process of growing into a person who can design and implement how a server works , rather than simply knowing 'how to use it'!

Features of this course

📌 A course based on an engine clone project that implements all the core structures of Express.js.

📌 Visualize and explain the operating principles by line of code without abstract concepts

📌 Detailed implementation of security processing and error handling that can be used effectively in practice

📌 All course materials and test codes provided , so you can learn by running them yourself.

📌 Grow into a server developer who knows how to create , not just a developer who simply writes

I recommend this to these people

Anyone who has used Node.js and Express but is curious about the internal principles

This is suitable for those who want to understand concepts such as app.use , app.get , req , and res from the perspective of implementation rather than simple usage.

Developers who want to set up a server directly without a framework

This course is for those who want to learn how a real server works by implementing routers, middleware, static file processing, and body parsers.

Anyone who wants to become a server developer with structural thinking

This is useful for those who want to structurally understand the entire request processing flow from request → middleware chain → router → response.

For those who want to move beyond simply 'knowing how to use' the function

This is suitable for those who want to deeply understand the concepts by creating them themselves rather than memorizing and using the functions of Express.js .

Anyone who wants to create a bridge with various server frameworks

The theory you learn through Express.js will also be of great help in understanding other web frameworks such as Spring, Flask, Fastify, and ASP.NET Core .

Computer science majors and job seekers who want to strengthen both their portfolio and practical skills

Ideal for anyone looking to build their portfolio with a custom-built Express.js clone and build a solid foundation of server knowledge from basics to practical use .

After class

  • You will gain the skills to design and implement the entire web server process yourself, without Express.js.

  • You will gain a complete understanding of the flow of HTTP from request to response in Node.js, code by code.

  • You will learn the fundamentals of server development by implementing core practical functions one by one, such as routing, middleware chaining, request parsing, and static file serving.

  • By understanding the internal workings of server frameworks, the design philosophy of other frameworks such as Fastify, NestJS, Django, and Spring Boot can be naturally connected.


  • You will gain the ability to modularize complex functions into smaller units and refactor them into maintainable structures.

  • In addition to Express.js, you will be able to understand and explain the structure of how a web server engine receives requests and processes responses at a design level.

  • The lecture deliverables themselves will serve as a portfolio, and you can state in your application that you have personally implemented an 'Express.js clone project'.

Learn about these things.

Designing the createApplication function
We design a core controller structure that configures the starting point of app object, and includes the settings store, router, and middleware registration functions. This allows a single app instance to drive the entire server.

Implementing a middleware chain

You will directly implement the middleware continuous execution flow using next() , visualize the structure in which each middleware intercepts and processes requests, and acquire fundamental concepts. It is designed to help you understand systematically by comparing it to the hospital treatment flow.

Implementing a static file server

It implements a complete static server that streams files using fs.createReadStream() , automatically determines the MIME type for Content-Type , and includes security logic to prevent path traversal attacks.

Creating a JSON, URL-Encoded Body Parser

We will implement a full-fledged middleware that receives HTTP request body as a stream, incrementally accumulates data using data and end events, and then performs JSON parsing or URL decoding.

Router design and dynamic routing handling

You will learn how to directly match URL patterns like GET /users/:id , implement logic to put matched values into req.params , and fully understand the path-based handler execution flow, which is the core function of the router.

Implementing error handling middleware

We implement a 4-argument middleware with the structure function(err, req, res, next) and build a common error handling flow by safely catching synchronous errors with try...catch and asynchronous errors with Promise.reject() .

Template rendering processing

Experience the complete server-side rendering process from start to finish, from implementing res.render() method directly by integrating the EJS template engine to dynamically generating HTML on the server.

Implementing express.Router() function

We create sub-router instances through createRouter() function and connect them hierarchically to the main app, so that they can be managed in modules even in large-scale API structures.

Architecture Improvement

We implement an architecture structure that prevents sharing of global state, hides settings and internal modules, and enhances security by utilizing the Singleton pattern and IIFE . We also improve the engine to have practical maintainability and extensibility through middleware integration and structural separation.

API Test Automation

Ensure test stability by creating automated test scripts that send requests to real servers using http.request() parse the response body, and output the results along with status codes.

Things to note before taking the class

Learning Materials

  • Provides materials including source code, test scripts, and EJS templates used in all classes

  • We also provide intermediate step-by-step code so you can practice along with the exercises.


Player Knowledge and Notes

  • You should be familiar with basic JavaScript syntax . You need to understand variable declarations, function definitions, array/object manipulation, and asynchronous processing (Promises, etc.).

  • It would be helpful to have a basic understanding of Node.js environment setup and module system (e.g. CommonJS). It would be easy if you know how to run a local server, require and module.exports do, etc.

  • If you have experience using Express.js , you will understand the core much faster. This course focuses on implementing the working principle directly rather than simply using it.

  • This course focuses on the process of implementing from scratch , rather than providing complete code or packages. You will learn the structure and principles by writing code yourself.

  • We recommend that you take the course 'Learning Express.js Properly: Part 1 [Basics] from Basics to Advanced'. In that course, the basic structure and usage of Express.js are covered first, and this course is an advanced course that implements the internal structure based on that.

Recommended for
these people

Who is this course right for?

  • A developer who wants to grow one step further from just having used Express.js.

  • An aspiring backend developer who wants to accurately understand the internal operating principles of a server

  • A learner who wants to learn the structural concepts of web frameworks by directly implementing them

  • A job seeker looking for a meaningful clone project to include in their portfolio

  • Developers with experience in other frameworks like Django, Flask, Spring Boot, who want to understand Node.js server structure.

  • Aspiring to be a 'developer who can explain how it works' rather than just a 'developer who knows how to use it.'

  • A frontend developer wanting to better understand server-client flow during web development.

  • A beginner who wants to experience truly building their own backend structure, moving beyond 'development solely based on memorized functions'.

  • Career changer, not a CS major, aiming for a deep web development foundation.

  • Front-end or full-stack developers who want to utilize JavaScript more deeply in practice.

Need to know before starting?

  • Basic JavaScript Syntax

  • Node.js experience

  • Experience with Express.js (Optional)

  • Network and HTTP Concepts (Optional)

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현재는 약 30명의 현직 개발자와 컴퓨터공학 전공 대학생들이 각자의 전문 분야를 맡아, 입문부터 실전까지 아우르는 커리큘럼을 직접 설계하고 강의합니다. 단순한 지식 전달을 넘어, 진짜 개발자의 시선으로 배우고 함께 성장할 수 있는 환경을 제공합니다.

“진짜 개발자는, 진짜 개발자에게 배워야 합니다.”

저희는 웹 개발의 전 과정을 처음부터 끝까지 체계적으로 다루되, 이론에 머무르지 않고 실습과 실전 중심의 피드백을 통해 실력을 키워드립니다.
수강생 한 사람, 한 사람의 성장을 함께 고민하고 이끌어가는 것이 우리의 철학입니다.

🎯 우리의 철학은 분명합니다.
"진정한 배움은 실천에서 오고, 성장은 함께할 때 완성된다."

개발을 처음 시작하는 입문자부터, 실무 능력을 키우고 싶은 취업 준비생, 진로를 탐색 중인 청소년까지.
우리동네코딩 스튜디오는 모두의 출발점이자, 함께 걷는 든든한 동반자가 되고자 합니다.

이제, 혼자 고민하지 마세요.
우리동네코딩 스튜디오가 여러분의 성장을 함께하겠습니다.


Welcome to Neighborhood Coding Studio!

Neighborhood Coding Studio was founded by a team of developers who studied computer science at top North American universities such as Carnegie Mellon, the University of Washington, the University of Toronto, and the University of Waterloo, and went on to gain hands-on experience at global tech companies like Google, Microsoft, and Meta.

It all began as a study group formed by computer science students across the U.S. and Canada, created to grow together by sharing knowledge, solving problems, and learning from one another.
Though we were attending different schools in different time zones, the experience was so meaningful that it led us to one simple thought:

“What if we shared this way of learning with others?”

That thought became the foundation of Neighborhood Coding Studio.

Today, we are a team of around 30 active developers and computer science students, each taking responsibility for their area of expertise—designing and delivering a curriculum that spans from foundational knowledge to real-world development.
We’re not just here to teach—we’re here to help you see through the lens of real developers and grow together.

“To become a real developer, you must learn from real developers.”

Our courses take you through the entire web development journey—from start to finish—focused on hands-on practice, real-world projects, and practical feedback.
We care deeply about each learner’s growth and are committed to supporting your path every step of the way.

🎯 Our philosophy is simple but powerful:
"True learning comes from doing, and true growth happens together."

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Neighborhood Coding Studio is here to be your launchpad—and your trusted companion on the journey.

You don’t have to do it alone.
Let Neighborhood Coding Studio walk with you toward your future in development.

Curriculum

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53 lectures ∙ (5hr 30min)

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    손정만

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    Average Rating 4.6

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    • nhcodingstudio
      Instructor

      감사합니다, 손정만님, 소중한 수강평과 좋은 평가 남겨주셔서 진심으로 감사드립니다! 🙏 여러분의 응원 덕분에 강의를 준비하는 큰 힘이 됩니다. 이번 강의를 통해 Express.js의 구조와 서버 엔진 설계 원리를 깊이 이해하셨다면, 앞으로는 백엔드 아키텍처, 데이터베이스, 서버 운영 등 더욱 실무적인 주제와 확장된 컨텐츠로 찾아뵐 수 있도록 계속 준비하겠습니다. 🚀 또한 감사와 응원의 마음을 전하며, 언제든 궁금한 점이 생기시거나 개발 관련해서 도움이 필요하실 때는 아래 오픈채팅방을 자유롭게 이용해 주세요. 함께 공부하시는 분들과도 소통 가능하고, 저도 자주 들러서 고민을 나누고 있습니다! 📮 오픈채팅방: [https://open.kakao.com/o/gC10Fnoh] 개발 여정을 언제나 진심으로 응원드리며, 다음 강의에서도 꼭 다시 뵐 수 있기를 기대합니다! 🌟

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