What is namespace in Typescript ? (original) (raw)

Last Updated : 17 Mar, 2025

In TypeScript, a namespace is a way to organize code logically and prevent naming conflicts between identifiers. It allows developers to group related functionalities, such as interfaces, classes, functions, and variables, within a dedicated scope.

Namespaces are particularly useful for structuring large applications, avoiding global scope pollution, and maintaining a clear hierarchy.

Declaring and Using a Namespace in TypeScript

Here’s a simple example demonstrating how to create and use a namespace in TypeScript:

JavaScript `

namespace Geometry { export class Circle { constructor(public radius: number) {}

area(): number {
  return Math.PI * this.radius ** 2;
}

} } const circle = new Geometry.Circle(5); console.log(circle.area());

`

• **Namespace Declaration: The Geometry namespace encapsulates the Circle class, ensuring that its members are scoped within this namespace.
• **Class Definition: The Circle class has a constructor to set the radius and a method area() to calculate the area of the circle.
• **Object Instantiation: An instance of Circle is created with a radius of 5.
• **Method Invocation: The area() method is called on the circle instance to compute and log the area.

**Output:

78.53981633974483

**More Examples of Namespace in TypeScript

**Declaring and Accessing a Simple Namespace

JavaScript `

namespace MyNamespace { export function myFunction() { console.log('This is my function in MyNamespace'); } }

MyNamespace.myFunction();

`

• **Namespace Declaration: MyNamespace is defined using the namespace keyword, encapsulating the myFunction function.
• **Function Definition: myFunction logs a message to the console.
• **Export Keyword: The export keyword makes myFunction accessible outside the MyNamespace namespace.
• **Function Invocation: myFunction is called using dot notation: MyNamespace.myFunction().

**Output:

This is my function in MyNamespac

**Declaring and Accessing a Nested Namespace

JavaScript `

namespace MyNamespace { export namespace MySubNamespace { export function myFunction() { console.log('This is my function in MySubNamespace'); } } }

MyNamespace.MySubNamespace.myFunction();

`

• **Nested Namespace Declaration: MySubNamespace is defined inside MyNamespace, creating a hierarchical structure.
• **Function Definition: myFunction logs a message to the console.
• **Export Keyword: The export keyword makes myFunction accessible outside the MySubNamespace namespace.
• **Function Invocation: myFunction is called using dot notation: MyNamespace.MySubNamespace.myFunction().

**Output:

"This is my function in MySubNamespace"

**Benefits of Using Namespaces

• **Organize Code: Namespaces help group related code together, making it easier to manage and maintain.
• **Prevent Conflicts: They avoid naming issues by keeping your code in its own unique space.
• **Hide Details: You can keep internal code hidden and only show the necessary parts to the outside world.
• **Break Down Code: Namespaces let you divide a large project into smaller, easier-to-manage pieces.

Namespaces vs. Modules in TypeScript

Here are the main differences between Namespaces and Modules in TypeScript: