Named Import vs. Default Import: How to Choose the Right One

In JavaScript, managing modules effectively is crucial for building maintainable and scalable applications. When working with JavaScript modules, default, and named imports are two primary ways to bring external code into your project.

This blog will help you understand the nuances of default imports, and named imports, and how to decide between the two for specific scenarios. By mastering these concepts, you'll learn to share code, optimize your import methods, and code efficiently.

What are JavaScript Modules?

JavaScript modules allow you to organize your code into smaller, reusable pieces. These modules can reside in different files or even within the same file, making them highly flexible for managing functionality and components. JavaScript modules support two primary ways of exporting values: default exports and named exports.

Default Export and Default Import

What is a Default Export?

A default export allows you to export one primary value from a module. When using a default keyword, you're telling JavaScript that this is the main item being exported from the file. Each module can have only one default export.

Here’s how you create a default export in a js file:

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1// file: button.js
2export default function ButtonComponent() {
3    return `<button>Click Me!</button>`;
4}

Understanding Default Import

A default import is the way to import this primary value from a module. When importing a default export, you can assign it any name since it’s the only export.

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1// file: app.js
2import MyButton from './button.js'; // Importing the default export
3console.log(MyButton());

In this example, even though the export default was named ButtonComponent, the default import allows renaming it to MyButton.

Named Exports and Named Imports

What are Named Exports?

Named exports allow you to export multiple values from the same module. These are explicitly named exports, meaning each exported value retains its name and must be referenced accordingly.

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1// file: utilities.js
2export function add(a, b) {
3    return a + b;
4}
5
6export function subtract(a, b) {
7    return a - b;
8}

What are Named Imports?

When using named imports, you use curly braces to specify which exported values you want to use. The names must match the exact names of the exported functions, variables, or components.

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1// file: app.js
2import { add, subtract } from './utilities.js'; // Named imports
3console.log(add(5, 3)); // Outputs: 8
4console.log(subtract(5, 3)); // Outputs: 2

If you need all the named exports, you can use a wildcard * as shown:

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1import * as Utils from './utilities.js';
2console.log(Utils.add(5, 3)); // Outputs: 8

Key Differences Between Default and Named Imports

Import Syntax

• Default imports: No curly braces, any name can be assigned.

• Named imports: Use curly braces and require exact names.

Export Flexibility

• A file can have only one default export.

• A file can have as many named exports as needed.

Use Cases

• Use default export for the main functionality of a single file (e.g., a button component).

• Use named exports when exporting multiple things (e.g., utility functions) from one file.

Using Default and Named Imports Together

You can combine default and named imports in the same statement:

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1// file: app.js
2import ButtonComponent, { add, subtract } from './utilities.js';
3console.log(ButtonComponent());
4console.log(add(2, 3));

Final Thoughts!

Choosing between named import vs default import depends on the nature of your javascript modules. A default export is ideal for one default export per module, while named exports allow you to export multiple values from a single file. By understanding these distinctions, you’ll not only code efficiently but also make your projects more maintainable. Remember to always check the syntax and the module structure to avoid errors.

Embrace both default and named imports to unlock the full potential of modular development in JavaScript.