TypeScript Academy · Lesson

Type-Only Imports and Exports

Use import type to avoid runtime overhead.

Lesson 3 of 413 steps

Type-Only Imports and Exports is a free TypeScript Academy lesson on CoddyKit. This is lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the TypeScript Academy learning path, and your progress syncs across the web and the CoddyKit app. The TypeScript Academy course includes 4 lessons in total.

Welcome

Type-only imports and exports (import type / export type) were introduced in TypeScript 3.8 to give developers explicit control over what is a runtime dependency and what is only a type.

Why Type-Only Matters

Regular imports may include runtime code. If you only need the type, the import can be erased entirely from the compiled output.

import { User } from './models'; // includes runtime binding
import type { User } from './models'; // compile-time only, erased

Syntax for import type

Place `type` after the `import` keyword. You cannot use the imported name as a value.

import type { ApiResponse } from './api-types';

function handleResponse(res: ApiResponse<User>): void {
  // ApiResponse used as type annotation only
}

Syntax for export type

Use `export type` to explicitly mark exports as type-only.

// user.types.ts
export type UserId = string;
export type { User, UserRole };

Inline Type Import

TypeScript 4.5+ allows marking individual imports as type-only within a regular import statement.

import { type User, createUser } from './user';
// User is type-only, createUser is a runtime value

Circular Dependency Resolution

Type-only imports can break circular dependency issues because they don't create runtime bindings.

verbatimModuleSyntax

TypeScript 5.0 introduced `verbatimModuleSyntax`. With it enabled, you MUST use `import type` for type-only imports to prevent bundler confusion.

// tsconfig.json
{ "compilerOptions": { "verbatimModuleSyntax": true } }

importsNotUsedAsValues

The `importsNotUsedAsValues` compiler option (superseded by verbatimModuleSyntax) controls how TypeScript handles unused value imports.

Benefits in Bundlers

Bundlers like Vite and esbuild use `import type` markers to skip processing type imports, improving build speed.

Type-Only Re-exports

Re-export types without including their runtime module.

// public-api.ts
export type { User, UserRole } from './internal-user';
export { createUser } from './internal-user'; // runtime

Error: Cannot Use import type as Value

Using a type-only import as a runtime value is a compile error.

import type { User } from './user';
// const u = new User(); // Error — User was imported as type-only

Quick Check

When should you use `import type` instead of a regular `import`?

Answer it in the interactive lesson

Recap

Use `import type` and `export type` for type-only imports and exports. They are erased at compile time, prevent runtime dependency on type files, and are required when verbatimModuleSyntax is enabled.

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Frequently Asked Questions

Is the “Type-Only Imports and Exports” lesson free?

Yes — the full text of “Type-Only Imports and Exports” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the TypeScript Academy course, upgrade to CoddyKit PRO. The TypeScript Academy course includes 4 lessons in total.

What will I learn in “Type-Only Imports and Exports”?

Use import type to avoid runtime overhead. You practise TypeScript Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start TypeScript Academy?

No prior experience is required. TypeScript Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 3 of 4.

How long does the “Type-Only Imports and Exports” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this TypeScript Academy lesson?

Yes. Every TypeScript Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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