JavaScript Modules 4

Question 1

What is an import map used for in browser-based ES modules?

Accepted Answer

Resolving bare module specifiers to URLs

Answer

An import map is a JSON configuration that tells the browser how to resolve bare specifiers like `'react'` to actual URLs.

Question 2

When using dynamic import inside an async function, which pattern is correct?

Accepted Answer

const mod = await import('./mod.js');

Answer

Since `import()` returns a Promise, you must `await` it inside an async function to get the module namespace object.

Question 3

Which statement about ES module scope is correct?

Accepted Answer

Each module has its own scope; top-level variables are not global

Answer

ES modules have their own scope, so top-level declarations do not pollute the global namespace.

Question 4

What happens when two modules import the same module in ES modules?

Accepted Answer

The module is evaluated once and the same instance is shared

Answer

The module system caches modules after the first evaluation, so all importers share the same module instance.

Question 5

Which syntax is used to conditionally load a module based on a runtime condition?

Accepted Answer

const mod = condition ? await import('./mod.js') : null;

Answer

Dynamic `import()` can be used inside expressions and conditionals, making it suitable for conditional or lazy loading.

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