Slide 1 / 20
What Is React and Why Use It?
React is a library for building fast, component-based user interfaces with reusable pieces.
A
AiTechWorlds
AiTechWorlds
React is a popular JavaScript library for building user interfaces with reusable components. This visual guide explains components, JSX, props, state, the useState and useEffect hooks, the virtual DOM, and key React patterns.
React is a library for building fast, component-based user interfaces with reusable pieces.
A component is a reusable function that returns UI based on its inputs.
JSX lets you write HTML-like markup inside JavaScript, which React turns into UI.
Props are inputs passed in from outside; state is data a component manages itself.
useState adds local, reactive state to a function component.
useEffect runs side effects like data fetching after render, controlled by dependencies.
Render different UI based on conditions using ternaries or && in JSX.
Map arrays to elements and give each a stable key so React tracks them efficiently.
Attach handlers like onClick with camelCase props that receive event objects.
Move shared state to the closest common parent so siblings can stay in sync.
React builds a lightweight copy of the DOM and updates only what actually changed.
A component re-renders when its props or state change — keep this efficient.
useRef stores a mutable value or DOM reference without causing re-renders.
Context shares values like theme or user across components without prop drilling.
Custom hooks extract reusable stateful logic into your own use-prefixed functions.
They memoize values and functions to avoid unnecessary recalculation and re-renders.
Controlled inputs are driven by state; uncontrolled inputs read values from the DOM.
Fetch data inside useEffect or with a data library, handling loading and error states.
Mutating state directly, missing keys, and wrong dependency arrays are frequent bugs.
React is the UI library; Next.js is a framework adding routing, rendering, and full-stack features.
Join AiTechWorlds on Telegram and get daily AI tips, prompt engineering templates, coding resources, and exclusive content — 100% free!
No spam. Leave anytime.
