Web Development Full Course 2026 | Build Real Projects (Node.js, Express, React, MongoDB, SpringBoot, AI , System Design) - ReactJS Full Course | What is ReactJS | React JS Tutorial for Beginners | ReactJS Full Course #1

Welcome to the first episode of the only React JS course you'll ever need. If you've mastered HTML, CSS, and JavaScript but are tired of tutorials that just show you the 'how' without the 'why', you're in the right place. We're throwing out memorization and building a deep, fundamental understanding of React from First Principles. In this first video, we go back to the beginning. Before we write a single line of JSX, we explore the core problem React was created to solve. We'll compare the old, imperative way of building web apps with React's powerful declarative model, solidifying the one concept that rules them all: UI = f(state). ✨ IN THIS VIDEO, YOU WILL LEARN: (Using timestamps helps with SEO and user experience) The Problem with Modern Web Apps The "Old Way": Manual DOM Manipulation (Imperative) The Core Flaw: Why Imperative UI is Prone to Bugs React's Big Idea: The Declarative Mindset Shift The Golden Rule: UI = f(state) Explained The Bedrock: React.createElement (NO JSX!) First Principles: Why React and ReactDOM are Separate Libraries What's Coming Next in Episode 2 (Components & JSX) --- 🧠 OUR METHODOLOGY (FIRST PRINCIPLES): Instead of memorizing a list of React features, we will build our knowledge from the ground up. Each new concept will be connected to a core truth about managing UI complexity. This method ensures you don't just know how to write React code—you'll know how to THINK in React. ✅ WHO IS THIS FOR? - Developers who have mastered HTML, CSS, and vanilla JavaScript. - Learners who want to understand the "why" behind the code. - Anyone who has tried other React tutorials and felt like they were just copying and pasting. 0:00 Introduction to React 1:50 What is React 3:17 Problem 1: Creating Elements with Raw DOM 6:36 Problem 2: Repetitive Code Issues 8:33 Solution: Designing a Reusable createElement Function 11:44 Implementing Custom createElement 16:33 Handling Nested Styles (Object.assign) 22:15 What React Really Is 25:59 What ReactDOM Does 40:20 React vs ReactDOM 45:39 Why They’re Separate (Native, PDF, etc.) 53:12 Building a Custom ReactDOM Renderer 1:03:59 React 18 Rendering (createRoot) 1:06:10 Conclusion – Why JSX Matters #ReactJS #LearnReact #ReactTutorial #WebDevelopment #JavaScript #FirstPrinciples #ReactForBeginners Visit Strike: https://strikes.in/ Class start from 1 december Visit Coder Army Website: https://coderarmy.in/#home Enroll in Our Premium Courses: DSA: https://strikes.in/course/combo Web Dev: https://coderarmy.in/#home AI: https://strikes.in/course/689ee05f1d8fc292bd27df7c HLD Course: https://rohittnegi.akamai.net.in/new-courses/8-high-level-design-course Course start date: 1 september Timing: 6pm (Mon-fri) Hackathon will be organised after course completion Join Premium Whatsapp Group: https://whatsapp.com/channel/0029Va6H0tbHVvTbcuT99Y1f Class Notes : https://www.notion.so/Lecture-01-Introduction-To-React-2b03a78e0e2280c6b345f2ee06dc25de?source=copy_link Code Link: https://github.com/coderarmy-notes/mern-stack-course Twitter: https://x.com/rohit_negi9?s=21 Channel: ‪@CoderArmy9‬ Buy Our Premium Course of Web dev+Blockchain+HLD+DSA: https://rohittnegi.akamai.net.in/new-courses/4-web-development-block-chain (5500 only) Time Stamp: #javascript #webdevelopment #mernstack