React doesn't render like the old-school days of HTML or jQuery.
👉 It follows a declarative approach — where you don't tell the browser how to change things. Instead, you describe what you want the UI to look like, and React handles the rendering behind the scenes.
🤖 So... How Does React Actually Render?
When you write a React component like:
const App = () => <h1>Hello from Virendana</h1>;
You're not manipulating the DOM directly.
Instead, you're telling React:
"Hey, here's what I want the UI to look like. You figure out how to show it."
That's declarative rendering — the React way.
🧠 What is the Virtual DOM in React?
The Virtual DOM is a lightweight, in-memory copy of the real DOM.
- React builds a virtual snapshot of your UI
- When something changes (state/props), it compares the new snapshot with the old one
- Then it only updates what's changed, not the entire page
👉 This process is called Reconciliation, and it makes React blazing fast ⚡.
🖼️ React's Rendering Process: Behind the Scenes
Here's what happens when React renders a component:
- Component receives props and state
- React creates a virtual DOM snapshot (like a blueprint)
- React compares the old snapshot with the new one
- Only the differences (diffs) are updated in the real DOM
- The browser sees the change — fast and smooth
That snapshot includes:
- The full JSX structure
- Current state and props
- Any active event handlers
- UI description based on the logic
🧱 Mounting the App in the Real DOM
To tell React where to render your app, you use the createRoot function from the React DOM library:
import { createRoot } from 'react-dom/client';
import App from './App';
const rootElement = document.getElementById('root');
const root = createRoot(rootElement);
root.render(<App />);
This mounts your React application into the <div id="root"></div> in your HTML.
🧪 Quick Notes
- This is usually auto-handled when you use tools like Vite or Create React App
- But it's important to understand how React starts the rendering pipeline
- Only after calling
render()will your components show up on screen
🔄 Declarative vs Imperative Rendering (React's Superpower)
| Style | Imperative (Old Way) | Declarative (React Way) |
|---|---|---|
| How it works | You tell browser how to update DOM | You describe what UI should be |
| Example | element.innerHTML = "Hello" |
<h1>Hello</h1> |
| Control | Full manual DOM control | React handles diffing & updates |
| Performance | Slower with large apps | Faster with Virtual DOM |
✅ Summary: React Rendering Process
- React renders using a virtual DOM — not the real DOM directly
- Rendering is declarative — you describe what you want, React does the rest
- React keeps snapshots of your component's state/props/handlers
- Only diffs are updated — saving time, memory, and power
FAQs – React Rendering & Virtual DOM
1. What is React rendering?
It's the process where React updates the UI based on state/prop changes using the virtual DOM for performance.
2. What is the virtual DOM in React?
A lightweight copy of the real DOM. React uses it to track changes and update only what's necessary.
3. How does React know what to update?
React compares the previous virtual DOM snapshot with the new one (diffing) and applies minimal updates to the real DOM.
4. Why is React rendering faster than normal DOM manipulation?
Because it avoids full DOM reflows and repaints by using virtual DOM and batching updates.
5. Do I need to manually call render every time something changes?
Nope. React automatically re-renders the component when state or props change — thanks to its internal reactive system.