What is a namespace?
- TypeScript course
- Intermediate
- Lesson 54/89
- 4 min
Learn global scope grouping with namespace.
What is a namespace?
A namespace groups related code under a single name. It is declared with namespace Name { ... } syntax and members inside are exported with the export keyword. They are accessed from outside as Name.member.
namespace Hesap {
export function topla(a: number, b: number) {
return a + b;
}
}
console.log(Hesap.topla(2, 3)); // 5Without export it stays private
Members not marked with export inside a namespace are inaccessible from outside; they can only be used within the same namespace. This means a namespace provides encapsulation; you can hide internal logic from the outside world.
Practice Apply the namespace pattern
The compiled equivalent of a namespace structure can be expressed as a named object pattern. Define an object named Hesap with method topla(a: number, b: number): number returning a + b. Call it from outside as Hesap.topla with 2 and 3, and print the result with console.log.
Starter code
// Hesap adında bir nesne tanımla
// topla metodunu ekle, a ve b parametreli
// a + b döndürsün
// topla'yı 2 ve 3 ile çağır, sonucu yazdırSample solution
const Hesap = {
topla(a: number, b: number): number {
return a + b;
}
};
console.log(Hesap.topla(2, 3));Expected output
5
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How is a member inside a namespace accessed from outside?
- Via super.member
- Only by the member name directly
- Via dot notation as Ad.member Correct answer
- Via import { member } from "Ad"
Explanation: Namespace members are accessed via dot notation as Ad.member. import is for module imports; super is used in class inheritance; direct member access works only from inside the namespace.
2 Add export
namespace Hesap {
____ function topla(a: number, b: number): number {
return a + b;
}
}namespace Hesap {
export function topla(a: number, b: number): number {
return a + b;
}
}Explanation: To make a member inside a namespace accessible from outside you use export. public and static are for class members; default is for a module's default export.
3 Namespace parts
| Term | Meaning |
|---|---|
namespace Ad |
Namespace declaration |
export function |
Exported member |
Ad.üye |
Dot access |
export olmayan üye |
Only inside the namespace |