In React, the terms declarative and imperative describe two different styles of programming, particularly how you express logic and UI behavior.

Overview

Style	Description	React Style?
Imperative	You explicitly tell the program how to do something step by step.	Not preferred in React
Declarative	You describe what you want the UI to look like, and React figures out the how.	Preferred in React

Declarative Style (React’s Way)

In declarative programming, you write what the UI should be, and React handles updating the DOM when state changes.

Example:

function Greeting({ isLoggedIn }) {
  return (
    <h1>{isLoggedIn ? 'Welcome back!' : 'Please log in.'}</h1>
  );
}

Key Traits:

• You describe desired output (what should appear)
• React takes care of the UI updates
• Code is easier to read and reason about
• Focus is on what to show, not how to do it

Imperative Style (Manual DOM Manipulation)

In imperative programming, you directly tell the system how to do things — including manipulating the DOM yourself.

Example (Plain JavaScript):

const heading = document.createElement('h1');
if (isLoggedIn) {
  heading.textContent = 'Welcome back!';
} else {
  heading.textContent = 'Please log in.';
}
document.body.appendChild(heading);

Key Traits:

• You control the steps and sequence of DOM changes
• Harder to maintain and scale in large applications
• Not idiomatic in React

React Translates Declarative Code to Imperative Operations

Even though you write declaratively, under the hood, React performs imperative operations (e.g., DOM diffing and patching). But as a developer, you don’t have to manage these details.

Why Declarative Is Better in React

1. Cleaner Code: Less boilerplate, more readable
2. Less Bug-Prone: React manages DOM efficiently via the Virtual DOM
3. Easier State Handling: You bind UI directly to component state
4. More Maintainable: Easier to scale and test