Default exports vs named exports in Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to export the function as the default export.

Typescript

export default function greet() {
  return "Hello!";
}

Drag options to blanks, or click blank then click option'

Adefault

Bnamed

Cexported

Dmodule

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'named' instead of 'default' causes syntax errors.

Forgetting the export keyword entirely.

The keyword default is used to export a single default export from a module.

2fill in blank

medium

Complete the code to import the default export from the module.

Typescript

import [1] from './greet';
console.log([1]());

Drag options to blanks, or click blank then click option'

A{ greet }

B{ default }

C* as greet

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces for default imports causes errors.

Using '* as' syntax when not needed.

When importing a default export, you use a simple name without braces.

3fill in blank

hard

Fix the error in importing a named export from the module.

Typescript

[1]
console.log(greet());

Drag options to blanks, or click blank then click option'

Aimport * as greet from './greet';

Bimport greet from './greet';

Cimport { greet } from './greet';

Dimport default from './greet';

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to import named exports without braces.

Using 'default' keyword incorrectly in import.

Named exports must be imported using curly braces around the exact exported name.

4fill in blank

hard

Fill both blanks to export two named functions from the module.

Typescript

export function [1]() {
  return 'Hello';
}

export function [2]() {
  return 'Goodbye';
}

Drag options to blanks, or click blank then click option'

AsayHello

Bdefault

CsayGoodbye

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'default' as a function name for named exports.

Using the same name for both functions.

Named exports can be multiple functions with their own names.

5fill in blank

hard

Fill all three blanks to import a default export and two named exports from the module.

Typescript

import [1], { [2], [3] } from './messages';

console.log([1]());
console.log([2]());
console.log([3]());

Drag options to blanks, or click blank then click option'

AdefaultGreet

BsayHello

CsayGoodbye

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Putting named imports without braces.

Using wrong names for the imports.

You can import a default export with a name, and named exports inside curly braces.

Practice

1. What is the main difference between default export and named exports in TypeScript?

easy

A. Default export requires curly braces when importing, named exports do not.

B. Default export allows exporting one main value per file, named exports allow multiple exports by name.

C. Named exports can only export functions, default exports can only export objects.

D. Default exports are deprecated in TypeScript, named exports are preferred.

Solution

1. Step 1: Understand default export purpose

   Default export is designed to export a single main value from a file, like a main function or class.

2. Step 2: Understand named exports purpose

   Named exports allow exporting multiple values by their names, so you can import only what you need.

3. Final Answer:

   Default export allows exporting one main value per file, named exports allow multiple exports by name. -> Option B

4. Quick Check:

   Default export = one main, Named exports = multiple [OK]

Hint: Default = one main export, named = many exports by name [OK]

Common Mistakes:

• Confusing import syntax for default and named exports
• Thinking default export can export multiple items
• Assuming named exports require default keyword

2. Which of the following is the correct syntax to import a default export from a module named utils.ts?

easy

A. import utils from './utils';

B. import { utils } from './utils';

C. import * as utils from './utils';

D. import utils = require('./utils');

Solution

1. Step 1: Recall default import syntax

   Default exports are imported without curly braces using the syntax: import name from 'module'.

2. Step 2: Check options for correct syntax

   import utils from './utils'; matches this syntax exactly, importing the default export as utils.

3. Final Answer:

   import utils from './utils'; -> Option A

4. Quick Check:

   Default import has no braces [OK]

Hint: Default imports have no curly braces [OK]

Common Mistakes:

• Using curly braces for default imports
• Confusing import * as with default import
• Using require syntax in ES modules

3. Given the following module mathUtils.ts:

export default function add(a: number, b: number) { return a + b; }
export function multiply(a: number, b: number) { return a * b; }

What will be the output of this code?

import add, { multiply } from './mathUtils';
console.log(add(2, 3));
console.log(multiply(2, 3));

medium

A. NaN and 6

B. Syntax error

C. 5 and undefined

D. 5 and 6

Solution

1. Step 1: Understand import statements

   The default export function add is imported without braces, and the named export multiply is imported with braces.

2. Step 2: Evaluate function calls

   add(2, 3) returns 5, and multiply(2, 3) returns 6, so console logs 5 and 6.

3. Final Answer:

   5 and 6 -> Option D

4. Quick Check:

   Default + named import works = 5 and 6 [OK]

Hint: Default import no braces, named import with braces [OK]

Common Mistakes:

• Importing default export with braces
• Calling undefined functions due to wrong import
• Confusing output values

4. Consider this code snippet:

export default function greet() { return 'Hello'; }
export function greet() { return 'Hi'; }

What is the problem here?

medium

A. There is no problem; this code works fine.

B. Default export must be a variable, not a function.

C. You cannot have two functions with the same name exported, even if one is default.

D. Named exports cannot be functions.

Solution

1. Step 1: Identify duplicate function names

   Both the default export and named export use the same function name greet, which causes a conflict.

2. Step 2: Understand export rules

   Exports must have unique names; default export can be anonymous or named but cannot clash with named exports.

3. Final Answer:

   You cannot have two functions with the same name exported, even if one is default. -> Option C

4. Quick Check:

   Duplicate export names cause error [OK]

Hint: Default and named exports cannot share the same name [OK]

Common Mistakes:

• Assuming default export must be anonymous
• Thinking named exports can't be functions
• Ignoring duplicate export names

5. You have a file shapes.ts exporting multiple shapes and a default export for the main shape:

export interface Circle { radius: number; }
export interface Square { side: number; }
const defaultShape = { type: 'circle', radius: 5 };
export default defaultShape;

How would you import both the default shape and the Square interface correctly in another file?

hard

A. import defaultShape, { Square } from './shapes';

B. import { defaultShape, Square } from './shapes';

C. import { defaultShape } from './shapes'; import Square from './shapes';

D. import * as shapes from './shapes';

Solution

1. Step 1: Import default export without braces

   The default export defaultShape is imported without curly braces.

2. Step 2: Import named export with braces

   The named export Square interface is imported with curly braces.

3. Final Answer:

   import defaultShape, { Square } from './shapes'; -> Option A

4. Quick Check:

   Default no braces, named with braces [OK]

Hint: Default import no braces, named imports with braces [OK]

Common Mistakes:

• Using braces for default import
• Trying to import default as named
• Confusing import * as with default import