React Fundamentals
beginnerWhat You'll Learn
Theory
React is a JavaScript library for building user interfaces, developed by Meta. It introduced a component-based architecture and the Virtual DOM to make building interactive UIs predictable and efficient.
Component Model
React applications are trees of components. Each component is a self-contained piece of UI that manages its own state and renders output. Components can be nested, reused, and composed to build complex interfaces from simple building blocks.
Virtual DOM
The Virtual DOM is a lightweight JavaScript representation of the real DOM. When state changes, React creates a new Virtual DOM tree, diffs it against the previous one, and applies only the minimal changes to the real DOM. This reconciliation process is what makes React fast.
Declarative UI
React uses a declarative approach: you describe what the UI should look like for a given state, and React handles the updates. This contrasts with imperative approaches where you manually manipulate the DOM.
Why this matters
React's component model and declarative approach have transformed how modern web applications are built. Understanding these fundamentals prepares you to build scalable, maintainable user interfaces used by companies like Facebook, Netflix, and Airbnb.
What's next
In the next lessons, you'll dive deeper into each topic with hands-on examples and exercises.
Practical Examples
Exercises
Build a Profile Card Component
Create a functional component called ProfileCard that accepts name, title, and avatar props. Render them in a card layout with an h2 for the name, an h3 for the title, and an img for the avatar.
Expected Output:
A card displaying Alice as Developer with an avatar image