¶ React (JavaScript)
¶ Web Technologies
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React has a way of sneaking up on you. At first glance, it looks almost too simple—just a handful of functions and a pattern for composing UI. No sprawling set of commands. No dense configuration files. No cryptic template syntax. Just JavaScript, components, and an idea that feels obvious the moment you understand it: the UI should respond to state, not the other way around. Yet beneath that simplicity is a depth that has shaped modern web development more than any other JavaScript library of the last decade. React didn’t just become popular—it changed how people think about building interfaces.
This course, built across one hundred articles, exists because React deserves the kind of slow, thoughtful exploration that most developers never get the chance to experience. Too many people learn React in a rush, jumping from one quick tutorial to another, assembling bits of knowledge without ever forming a cohesive understanding. But React becomes truly powerful when you step back from the buzzwords and the ecosystem noise and start to appreciate its ideas. Not just the syntax, not just the hooks, but the philosophy underneath: declarative thinking, composability, predictable state, and the quiet discipline that leads to elegant, maintainable interfaces.
React’s story began in a time when front-end development was tangling itself into complexity. Interactive UI had become possible, but not pleasant. State was scattered everywhere. Events triggered chains of side effects that were difficult to track. Codebases grew brittle, and even frameworks designed to help often introduced their own layers of confusion. React appeared with a bold idea: re-render everything whenever your data changes. It sounded absurd to many developers, even technically reckless, until they realized something profound—React wasn’t doing brute force updates. It was using a lightweight representation of the UI, comparing old and new versions, and updating only what needed to change. This simple mental model made building complex interfaces not just manageable, but enjoyable.
If there’s a theme running through this entire course, it’s this: React rewards understanding. It rewards curiosity. And it rewards developers who want to think deeply about why things work the way they do. Over the next hundred articles, you’ll have the chance to build that understanding gradually, piece by piece, until the library feels less like a toolkit and more like a natural extension of your own thinking.
We begin with React’s heart: components. Not the fancy ones, not the complex ones—just the idea itself. A component is a function that takes state and returns UI. It’s almost poetic how much power sits in that simplicity. Components let you break a huge interface into smaller pieces, each responsible for its own behavior. They encourage clarity. They invite reuse. They enforce a way of thinking where each part of your application has a single responsibility and a predictable lifecycle.
From there, we move into state—useState, useReducer, and the subtle art of designing state that leads to predictable UI rather than accidental complexity. Managing state well is one of the defining skills of React development. Too little structure, and the application becomes untraceable; too much, and you lose the fluidity that React encourages. The early articles will help you develop an intuition for this balance, showing how good state design leads directly to simpler, clearer components.
Soon enough, we’ll explore effects. useEffect is one of the most misunderstood tools in React, not because it’s flawed, but because many people reach for it without understanding what it actually represents. Effects are React’s way of acknowledging the real world—network calls, subscriptions, timers, external APIs. They handle everything that doesn’t happen in pure rendering. In this course, you’ll learn not just how to use effects, but how to avoid the pitfalls, how to recognize when you don’t need one, and how to design components that stay predictable even as they interact with the messy nature of real data.
One of the most rewarding aspects of React is how it scales—not because the library grows more complicated, but because its principles hold steady. As applications expand, components remain components, state remains state, and composition remains the guiding structure. But surrounding React is a vast ecosystem of tools that help handle the parts React intentionally leaves open: routing, data fetching, styling, state management, testing, and build systems. Throughout the course, we’ll explore these tools thoughtfully. You’ll learn why React Router works the way it does, how state management libraries like Redux or Zustand fit into the bigger picture, and how modern frameworks like Next.js extend React into full-stack environments.
But we’ll approach these topics slowly, deliberately, and with the goal of clarity rather than hype. Tools come and go; good understanding lasts. The course is designed to help you not just adopt libraries, but evaluate them. Why might you choose one data-fetching solution over another? When should you use a context, and when does it become a burden? How do you structure a growing application so it stays enjoyable to work with? These questions matter just as much as syntax, if not more.
A significant part of the series will focus on real-world scenarios. It’s easy to learn React in isolation—counter examples, tidy forms, small layouts—but real projects rarely behave so nicely. We’ll take the ideas from the foundational articles and apply them to larger problems: complex UIs, dynamic data flows, dependent components, form systems, accessibility concerns, and performance constraints. You’ll learn how to design components that communicate clearly, how to manage state that crosses boundaries, how to minimize unnecessary re-renders, and how to avoid patterns that feel convenient in the moment but fragile in the long run.
And speaking of performance—React’s performance story is a subject worth understanding deeply. Many developers assume performance problems appear magically or that optimization requires tricks. In reality, most performance issues disappear once you understand how React renders, how reconciliation works, and how to structure components intelligently. We’ll explore memoization, batching, suspense, lazy loading, and the subtle influence of component boundaries on how efficiently React updates the UI. But this won’t be a tour of technical jargon. Instead, it will be a practical guide to seeing React’s rendering model clearly enough that optimization becomes intuitive rather than mysterious.
Toward the middle of the course, we’ll explore one of React’s defining ideas: declarative UI. It sounds like a buzzword, but it’s a profound shift in how developers think. Instead of telling the browser what to do step by step, you describe what the UI should look like, and React takes care of the rest. This mindset has influenced countless libraries and frameworks, and once you internalize it, you start writing code that feels lighter, more confident, and easier to reason about.
We’ll also discuss styling—one of those topics where personal preference meets technical trade-offs. From CSS modules to styled-components, Tailwind, inline styles, and utility-first approaches, you’ll learn how styling interacts with React’s component model and how to choose the patterns that suit your team, your project, and your long-term goals. Styling is more than a cosmetic layer; it’s part of how an application breathes.
And then there’s testing. React’s component-based architecture encourages testing naturally—each piece can be examined in isolation with predictable inputs and outputs. Over the course of this series, you’ll learn how to write tests that give you confidence instead of friction, how to approach testing state and effects, and how to design components that stay testable as they grow more complex. Tools like React Testing Library will make frequent appearances, not as obligations but as partners in building quality software.
As we move deeper into the later articles, the conversations become even more architectural. How do you structure a large codebase so that it stays maintainable after years? How do you decide which components belong together? How do you handle shared logic without creating tangled abstractions? How do you keep the mental load low when your application becomes big enough to have many contributors? These are the kinds of questions experienced developers share over coffee or at conference hallway conversations, and this course will bring those insights to you through thoughtful examples, discussions, and step-by-step reasoning.
The final stretch of the course will broaden the perspective beyond React alone. We’ll explore how React fits into the future of web development: server components, streaming architectures, hybrid rendering strategies, client/server boundaries, and how the evolution of React reflects the needs of the modern web. You’ll see how concepts like Suspense or Server Components aren’t arbitrary inventions but natural extensions of React’s core philosophy. Understanding these ideas doesn’t just make you a better React developer; it makes you a stronger engineer, period.
By the time you reach the end of this journey, React will no longer feel like a bag of tools—you’ll see it as a system of ideas. You’ll understand how to think in components, how to design state gracefully, how to architect complex interfaces without drowning in complexity, and how to build applications that feel sturdy, expressive, and deeply maintainable. You’ll carry these skills into every project you touch, long after the details of specific hooks or libraries evolve.
Most importantly, you’ll enjoy React more. That may sound quaint, but enjoyment matters. When a framework becomes intuitive, when patterns feel natural, when you can predict behavior effortlessly, coding shifts from a task into a craft. React, at its core, is a library built to make UI development delightful. This course exists to help you reach that experience—not by rushing, not by overwhelming, but by gradually revealing the clarity that has made React the cornerstone of modern front-end development.
So take a breath. Settle in. We have a long, rewarding journey ahead. Together, we’ll explore React not just as a tool, but as a way of thinking—one component, one idea, one insight at a time.
Let’s begin.
¶ React (JavaScript)
¶ Beginner Level
1. Introduction to React: What It Is and Why Use It?
2. Setting Up Your React Development Environment
3. Understanding the Basics: React Components
4. JSX Syntax and How It Works in React
5. Rendering Your First Component in React
6. State and Props in React: The Core Concepts
7. Event Handling in React: Handling User Interactions
8. Introduction to React Functional Components
9. Understanding React's Virtual DOM
10. Creating and Using React Class Components
11. Managing Component State with useState Hook
12. Passing Data Between Components with Props
13. Rendering Lists and Iterating with map() in React
14. Conditional Rendering in React
15. Understanding React’s Component Lifecycle
16. Handling Forms and User Input in React
17. Using Controlled vs. Uncontrolled Components in React
18. React Forms: Handling Validation and Submitting Data
19. Component Styling: Inline Styles, CSS, and CSS-in-JS
20. Building a Simple To-Do List App with React
21. Introduction to React Router: Navigating Between Pages
22. Working with Links and Navigation in React
23. Building a Multi-Page React Application with React Router
24. Understanding React’s useEffect Hook for Side Effects
25. Component Composition: Reusing Code and Nested Components
26. Error Boundaries in React: Catching and Handling Errors
27. Building a Simple Counter Application with React
28. Understanding React Keys in Lists
29. React Development Tools: Debugging and Profiling
30. Working with React DevTools for Efficient Development
31. Introduction to Functional Programming Concepts in React
32. Managing Side Effects with useEffect and Cleanup
33. Using useRef Hook for DOM References
34. Using useContext Hook for Global State Management
35. Using React Context API for Passing Data Globally
36. Managing Dynamic Class Names in React Components
37. Building a Simple Calculator with React
38. Best Practices for Organizing React Component Structure
39. Introduction to Component Testing in React
40. Unit Testing React Components with Jest
41. Using Snapshot Testing in React with Jest
42. React’s Strict Mode: Enabling Development Mode Features
43. Basic Optimizations in React for Better Performance
44. Building a Simple CRUD Application with React
45. Using Axios to Fetch Data from APIs in React
46. Displaying Data from API Requests in React Components
47. Understanding Promises and async/await in React
48. Handling Errors in Asynchronous Operations in React
49. Making API Calls with useEffect Hook
50. Managing Loading States with React
¶ Intermediate Level
51. React Router: Advanced Routing and Nested Routes
52. React and State Management: The Basics of Redux
53. Using Redux with React for Global State Management
54. The Redux Flow: Actions, Reducers, and Store
55. Connecting Redux with React Components
56. Handling Asynchronous Actions with Redux Thunk
57. Working with Redux DevTools for State Debugging
58. Memoization in React: Using useMemo and React.memo
59. React Hooks in Depth: useEffect, useContext, and Custom Hooks
60. Using React’s useCallback Hook for Optimizing Performance
61. Optimizing React Applications with Code Splitting
62. Lazy Loading Components in React with React.lazy()
63. Understanding Suspense in React for Lazy Loading
64. Building a Modal Component in React
65. Managing Component Side Effects with useEffect Hook
66. Handling Component Unmounting in React
67. Using Higher-Order Components (HOCs) for Code Reusability
68. Building Reusable Forms with React and Custom Hooks
69. React Context vs Redux: Choosing the Right State Management Tool
70. State Management with useReducer Hook in React
71. Introduction to TypeScript with React
72. Type Checking in React with PropTypes
73. Creating Custom Hooks in React for Code Reusability
74. Implementing Authentication in React Applications
75. Using React Context for Global State in Medium to Large Apps
76. Working with Custom React Hooks for Complex Logic
77. Form Handling with React Hook Form
78. Unit Testing React Components with Enzyme
79. Integration Testing with React Testing Library
80. Handling Multiple Input Fields in React Forms
81. React and WebSockets: Building Real-Time Applications
82. Building a Search Functionality in React with Debouncing
83. Form Validation in React with Custom Logic
84. Creating Pagination in React with Dynamic Content
85. Internationalization and Localization in React
86. Building a Responsive React App with Media Queries
87. Creating Dynamic Routes with React Router
88. Working with SVGs in React
89. Optimizing Images and Assets in React
90. Integrating Third-Party Libraries with React (e.g., Charts, Maps)
91. Building a Shopping Cart Application with React
92. Building a Blog Application with React
93. Integrating Firebase with React for Authentication and Database
94. Managing Authentication and Sessions with JWT in React
95. Form Data Submission in React with Fetch API
96. Building a Progressive Web App (PWA) with React
97. Service Workers in React for Offline Functionality
98. State Persistence with localStorage in React
99. Handling Multiple Forms in a Single React Application
100. Integrating React with External RESTful APIs