Difference Between a .js and .jsx File in React

React is a JavaScript library used for building user interfaces, especially for single-page applications. It uses a component-based structure that makes development more efficient and maintainable. In React, different file extensions are used for specific purposes: .js or .jsx for JavaScript and JSX code.

Understanding these extensions is important for improving code readability, fixing bugs in your project.

Difference Between a .js and .jsx File in React

Here is a detailed comparison of .js and .jsx files based on various features:

What are .js files in React?

The .js file is a file that contains standard JavaScript code. These files do not contain the UI related code and are used for writing the logics and the functions.

• Used for regular JavaScript code and logic.
• Does not include JSX (HTML-like syntax).
• Can be used for utility functions, state management, or simple React components.
• No extra tools needed to run.

Now, let us understand with the help of the example:

// MyComponent.js
import React from 'react';
const MyComponent = () => {
  return React.createElement('h1', null, 'Hello, World!');
};
export default MyComponent;

In this example:

• The component is created using React.createElement() instead of JSX.

What is (.jsx) files in React

JSX (JavaScript XML) is an extension of JavaScript that lets developers write HTML-like code inside JavaScript. Files with the .jsx extension usually contain components written in JSX, which React then converts into JavaScript function calls.

• Used for React components with JSX (HTML-like syntax).
• Includes JSX to define the UI structure.
• Mainly for creating and rendering the user interface.
• Requires tools like Babel to convert JSX into JavaScript.

Now, let us understand with the help of the example:

// MyComponent.jsx
import React from 'react';
const MyComponent = () => {
  return <h1>Hello, World!</h1>;
};
export default MyComponent;

In this example

• JSX is used to directly write HTML-like code inside the return statement, making the code more readable and concise.

Key Difference:

• .js File: Uses React.createElement() to manually create elements without JSX.
• .jsx File: Uses JSX syntax to create elements, which will be compiled into React.createElement() by tools like Babel.

When to Use a .js and .jsx File in React

Use .js When:

• You are writing pure JavaScript code (e.g., functions, utilities).
• You are writing React components without JSX.
• The file does not contain any JSX expressions, but it might be used in React components (e.g., configuration files, non-UI logic).

Use .jsx When:

• You are writing React components that use JSX syntax.
• The file contains JSX code that needs to be transformed into JavaScript by tools like Babel.
• You want to make it clear that the file contains React components written with JSX for easier readability and better maintenance.

Conclusion

In React, the use of .js and .jsx file extensions helps keep the codebase organized. The .js extension is typically used for general JavaScript files, such as utility functions and configuration settings, while .jsx is reserved for React components that contain JSX syntax.