TypeScript TypeScript Functions & Modules 3

Question 1

What does a dynamic `import()` call return in TypeScript?

Accepted Answer

A `Promise` that resolves to the module object, enabling lazy loading

Answer

Dynamic `import()` is an asynchronous operation that returns a `Promise<module>`, making it ideal for code splitting and loading modules on demand.

Question 2

Which function parameter type annotation is preferred over the broad `Function` type in TypeScript?

Accepted Answer

function run(fn: () => void): void

Answer

A specific function signature like `() => void` is preferred over the broad `Function` type because it enables TypeScript to check the argument count and types of the passed callback.

Question 3

What is the main use case for TypeScript `namespace` in modern code?

Accepted Answer

Grouping related declarations under a named scope, primarily in non-module (global) scripts

Answer

Namespaces group related code under a named scope to avoid global name collisions; in modern projects using ES modules, they are largely replaced by modules but still useful in global scripts.

Question 4

What is required to make TypeScript path aliases (configured via `paths` in `tsconfig.json`) work at runtime?

Accepted Answer

Both the `tsconfig.json` `paths` configuration AND a matching bundler or runtime loader configuration

Answer

TypeScript's `paths` only affects the type checker; at runtime, the bundler (e.g., webpack, Vite) or a Node.js path mapper must also be configured to resolve the aliases.

Question 5

What does setting `isolatedModules: true` in `tsconfig.json` enforce?

Accepted Answer

Every file must be treated as a module (have at least one `import` or `export`)

Answer

`isolatedModules` ensures each file can be transpiled in isolation without cross-file type information; files without any `import`/`export` are treated as global scripts and will cause an error.

TypeScript Practice Test

TypeScript Practice Test

TypeScript TypeScript Functions & Modules 3