Understanding JavaScript Exports: Default Export vs. Named Export

When working with JavaScript modules, especially in frameworks like React, understanding the difference between default and named exports is crucial for writing clean, maintainable code.
This article explains these two export types, their differences, and when to use each.

Default Export

A default export is used to export a single value from a module. This value can be a function, class, object, or primitive and doesn't need a specific name. You can import it using any name, providing flexibility in structuring your imports.

In the example below, InnerPage is defined as a function component and exported as the module's default export:

// InnerPage.js
const InnerPage = () => {
  return <div>Inner Page</div>;
};
export default InnerPage;

Then, when importing this component, you can use any name:

// ParentPage.js
import AnyName from './InnerPage';

// Usage
<AnyName />

The ability to rename the import can be useful, particularly if the name conflicts with another identifier (name) in your module.

Named Export

A named export allows you to export multiple values from a module. Each export must be imported using its exact name, encouraging clarity in your code.

Below is how you can define and export a component using a named export:

// InnerPage.js
export const InnerPage = () => {
  return <div>Inner Page</div>;
};

When importing this component, you must use its exact name:

// ParentPage.js
import { InnerPage } from './InnerPage';

// Usage
<InnerPage />

This strict naming helps avoid confusion and clarifies what is being imported, which is particularly helpful in larger codebases.

Key Differences

Flexibility vs. Explicitness

• default export offers more flexibility since you can import the exported value using any name. It is often used when a module has a single primary export.

import MyComponent from './MyComponent';

• named export encourages clarity, requiring you to use the exact name of the export. It is useful when a module exports multiple values.

import { MyComponent, AnotherComponent } from './components';

Usage Context

• default export is ideal for modules that export a single component, function, or value. It simplifies the import statement and keeps the code concise.

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

// App.js
import MyComponent from './MyComponent';

• named export is suitable for modules that export multiple components or values. It makes the import statements more descriptive and helps in maintaining consistency.

// components.js
export const MyComponent = () => { /* ... */ };
export const AnotherComponent = () => { /* ... */ };

// App.js
import { MyComponent, AnotherComponent } from './components';

Combining Default and Named Exports

You can also combine default and named exports in the same module. It can be useful when a module has a primary export along with some secondary exports.

// utilities.js
export const helperFunction = () => { /* ... */ };

const mainUtility = () => { /* ... */ };
export default mainUtility;

When importing, you can access both the default and named exports:

// App.js
import mainUtility, { helperFunction } from './utilities';

// Usage
mainUtility();
helperFunction();

Conclusion

Understanding the difference between default and named exports is essential for writing clear and maintainable JavaScript code. Use default exports for simplicity and flexibility when a module has a single primary export. Use named exports to promote explicitness and clarity, especially when dealing with multiple exports.
By mastering these concepts, you can create more modular, readable, and maintainable codebases, making collaboration and future maintenance easier.