In React.js, named exports and default exports are used similarly to how they are used in regular JavaScript modules, but they’re particularly useful for exporting React components and other functionalities within your application.

Named Exports in React.js:
With named exports, you can export multiple components or other functionalities from a single module and import them individually in other modules.

Example:

// MyComponent.js
export const MyComponent1 = () => { ... };
export const MyComponent2 = () => { ... };

// AnotherFile.js
import { MyComponent1, MyComponent2 } from './MyComponent';

Default Export in React.js:
With default exports, you export a single component or other functionality as the default export from a module. You can import the default export using any name of your choosing in the importing module.

Example:

// MyDefaultComponent.js
const MyDefaultComponent = () => { ... };
export default MyDefaultComponent;

// AnotherFile.js
import MyComponent from './MyDefaultComponent';
// Here, you can name MyComponent whatever you want, as it's the default export

It’s worth mentioning that both named exports and default exports are commonly used in React.js applications, depending on the specific use case and project structure. For smaller components or functionalities, default exports are often preferred, while named exports are useful for exporting multiple components or utilities from a single module.