Named vs default export

Node.jsJunior~3 min read

1. What "export" means in general

Export is the mechanism that lets a module "hand out" functions, variables, classes, and so on, so they can be imported in other files.

ES Modules have two types of exports:

Named export
Default export

2. Named exports

Lets you export several values from a module, each with its own name.

math.js

javascript

export const PI = 3.14;
export function add(a, b) {
  return a + b;
}
export function sub(a, b) {
  return a - b;
}

app.js

javascript

import { PI, add, sub } from './math.js';

console.log(PI);       // 3.14
console.log(add(2, 3)); // 5

You can export several items from one file. The import must use the exact same names as the export.

An alternative form:

javascript

const PI = 3.14;
function add(a, b) { return a + b; }
function sub(a, b) { return a - b; }

export { PI, add, sub };

This is equivalent to the previous example, just a grouped export.

3. Default exports

Lets you export only one value as the module's "main content".

logger.js

javascript

export default function log(message) {
  console.log('LOG:', message);
}

app.js

javascript

import log from './logger.js'; // no braces!
log('Hello'); // LOG: Hello

With a default export:

a module can have only one default export;
you can name it anything you like on import.

Another example:

javascript

export default class User {
  constructor(name) {
    this.name = name;
  }
}

Import:

javascript

import Person from './User.js'; // any name works
const user = new Person('Tim');

4. The key differences

Criterion	Named export	Default export
Count	Can export many values	Only one value
Import	With braces `{}`	Without braces
Name on import	Must match the original	Any name works
Syntax	`export const foo = ...` / `export { foo }`	`export default ...`
Importing everything	`import * as lib from './file.js'`	Not directly applicable
Semantics	Exports "many different parts" of a module	Exports the module's "main entity"
Examples	Utilities, constants, functions	The main class, function, or component

5. They can be combined

One module can hold both a named and a default export:

math.js

javascript

export const PI = 3.14;
export function add(a, b) { return a + b; }

export default function multiply(a, b) {
  return a * b;
}

app.js

javascript

import multiply, { PI, add } from './math.js';

console.log(multiply(2, 3)); // 6
console.log(PI);             // 3.14
console.log(add(5, 5));      // 10

6. Importing "everything" from a module

You can import the whole content under one name:

javascript

import * as math from './math.js';

console.log(math.PI);            // 3.14
console.log(math.add(2, 3));     // 5
console.log(math.default(2, 3)); // 6, the default is reached via .default

7. Common mistakes

Mistake	Cause	Fix
`SyntaxError: The requested module ... does not provide an export named`	The wrong name when importing a named export	Use the exact names
`default is not exported`	Trying to import a default that doesn't exist	Check that you export it via `export default`
`Cannot use import statement outside a module`	The file isn't ESM	Add `"type": "module"` to `package.json` or use `.mjs`

8. When to use which

Scenario	Export type
A module with several utilities	Named
One main class / component	Default
A library with an API	Combined (default + named)

Examples:

React → export default React; export { useState, useEffect }
Axios → export default axios; export { AxiosError }

9. Conceptually

Named exports are "many tools from a set" (everything is explicit, the IDE helps, autocomplete works).
A default export is "the module's main entity" (convenient when a file is responsible for one central object).

Quick summary

Characteristic	Named export	Default export
Count	Several	One
Import	`import { x } from`	`import x from`
Name	Must match	Any name
IDE hints	Works great	Sometimes lost
Use case	Utilities, functions, constants	The main class or component
Combining them	Works together	Works together

In one sentence

Named exports let you export several entities under their own names, while a default export is for the module's single "main" entity, which can be imported under any name.

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