How to export a Type in TypeScript

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Borislav Hadzhiev

Last updated: Mar 10, 2022

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Export a Type in TypeScript #

Use a named export to export a type in TypeScript, e.g. export type Person = {}. The exported type can be imported by using a named import as import {Person} from './another-file'. You can have as many named exports as necessary in a single file.

Here is an example of exporting a type from a file called another-file.ts.

another-file.ts
// 👇️ named export export type Person = { name: string; country: string; };

Note that using export on the same line as the type's definition is the same as exporting the type as an object after it has been declared.

another-file.ts
type Person = { name: string; country: string; }; // 👇️ named export export { Person };

Here is how we would import the type in a file called index.ts.

index.ts
// 👇️ named import import { Person } from './another-file'; const person: Person = { name: 'James Doe', country: 'Germany', };

Make sure to correct the path that points to the another-file module if you have to. The example above assumes that another-file.ts and index.ts are located in the same directory.

For example, if you were importing from one directory up, you would do import {Person} from '../another-file'.

We wrapped the name of the type in curly braces when importing it - this is called a named import.

TypeScript uses the concept of modules, in the same way that JavaScript does.

In order to be able to import a type from a different file, it has to be exported using a named or default export.

The example above uses named exports and named imports.

The main difference between named and default exports and imports is - you can have multiple named exports per file, but you can only have a single default export.

If you try to use multiple default exports in a single file, you would get an error.

index.ts
type Person = { name: string; country: string; }; type Employee = { id: number; salary: number; }; // ⛔️ Error: A module cannot have // multiple default exports.ts(2528) export default Person; export default Employee;

IMPORTANT: If you are exporting a a type, or a variable (or an arrow function) as a default export, you have to declare it on 1 line and export it on the next. You can't declare and default export a variable on the same line.

Having said that, you can use 1 default export and as many named exports as you need in a single file.

Let's look at an example that exports types and uses both - default and named exports.

another-file.ts
// 👇️ named export export type Person = { name: string; country: string; }; type Employee = { id: number; salary: number; }; // 👇️ default export export default Employee;

And here is how you would import the two types.

index.ts
// 👇️ default and named imports import Employee, { Person } from './another-file'; const person: Person = { name: 'James Doe', country: 'Germany', }; const employee: Employee = { id: 1, salary: 200, };

Notice that we didn't wrap the default import in curly braces.

We used a default import to import the Employee type and a named import to import the Person type.

You can only have a single default export per file, but you can have as many named exports as necessary.

In my experience, most real world codebases exclusively use named exports and imports, because they make it easier to leverage your IDE for autocompletion and auto-imports.

You also don't have to think about which members are exported with a default or named export.

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