Default exports in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a default export in JavaScript modules?

A default export is a way to export a single value or entity from a module so that it can be imported without using curly braces. It represents the main exported value of the module.

beginner

How do you write a default export for a function named greet?

You write: <pre>export default function greet() {<br>  console.log('Hello!');<br>}</pre> This exports the <code>greet</code> function as the default export.

beginner

How do you import a default export from a module named <code>math.js</code>?

You write: <pre>import anyName from './math.js';</pre> You can choose any name for the imported value because it is the default export.

beginner

Can a module have more than one default export?

No, a module can only have one default export. Trying to export more than one default will cause an error.

intermediate

What is the difference between default export and named export?

Default export exports a single main value without curly braces when importing. Named exports export multiple values and require curly braces when importing.

How do you import a default export from a module?

A import { value } from 'module';

B require('module').value;

C import * as value from 'module';

D import value from 'module';

Default exports are imported without curly braces using: import value from 'module';

Which of the following is a correct way to export a default value?

A export 42 as default;

B export { default: 42 };

C export default 42;

D export default = 42;

You export a default value simply by writing: export default 42;

Can a module have multiple default exports?

A No, only one default export is allowed.

B Yes, but only two.

C No, default exports are not allowed.

D Yes, unlimited default exports.

A module can only have one default export.

What happens if you import a default export with a different name?

A It causes an error.

B It works fine; you can rename default imports.

C It imports nothing.

D It imports all named exports.

Default exports can be imported with any name you choose.

Which syntax imports both default and named exports from a module?

A import defaultExport, { namedExport } from 'module';

B import { defaultExport, namedExport } from 'module';

C import * as all from 'module';

D import defaultExport from 'module';

You import default and named exports together like this: import defaultExport, { namedExport } from 'module';

Explain what a default export is and how it differs from named exports.

Think about how you import the main thing from a module.

Describe how to export and import a default function from a JavaScript module.

Focus on the function keyword and import naming.