Summary - Namespaces

Write a legacy-style library header with namespaces.

Summary - Namespaces

Namespaces are the legacy pattern for grouping related code in the global scope. They are declared with namespace Name, members are exported with export, they can be nested, and accessed as Outer.Inner.member. Modern projects prefer modules; namespaces are still useful for porting legacy libraries.

namespace Kutuphane {
  export namespace Matematik {
    export function topla(a, b) { return a + b; }
  }
}
Kutuphane.Matematik.topla(2, 3);

Exercise Legacy-style library header

Using the nested object pattern that is the compiled equivalent of a nested namespace structure, define an object Kutuphane with an inner object Matematik. Inside Matematik, place methods topla(a: number, b: number): number and carp(a: number, b: number): number; topla returns a + b, carp returns a * b. Call them from outside via the dot chain with 2 and 3, printing the results on separate lines.

Show example solution

const Kutuphane = {
  Matematik: {
    topla(a: number, b: number): number {
      return a + b;
    },
    carp(a: number, b: number): number {
      return a * b;
    }
  }
};
console.log(Kutuphane.Matematik.topla(2, 3));
console.log(Kutuphane.Matematik.carp(2, 3));

Test yourself

In which case might a namespace be preferred over a module?
- When starting a modern web application
- When writing an ES-module-compatible library
- When writing a single-file utility
- When setting up a new multi-file project
Show answer

When writing a single-file utility — For single-file utilities, namespaces can still be practical. For multi-file new projects, modern web apps, and ES-module libraries, modules are preferred.

Access with the outer namespace name

namespace Kutuphane {
  export namespace Matematik {
    export function topla(a: number, b: number): number {
      return a + b;
    }
  }
}
console.log(____.Matematik.topla(2, 3));

Show answer

namespace Kutuphane {
  export namespace Matematik {
    export function topla(a: number, b: number): number {
      return a + b;
    }
  }
}
console.log(Kutuphane.Matematik.topla(2, 3));

Match namespace concepts

namespace Ad

Global scope grouping
export namespace Ic

Inner namespace export
Dis.Ic.üye

Dot chain access
modern projelerde module

Modern recommendation

Next lesson: What is .d.ts?

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