TypeScript Object Interfaces vs. Intersections

TypeScript offers several features when it comes to defining complex data structures. In TypeScript, Object Interface and Intersections are two different features that serve different purposes when it comes to defining complex data structures.

Object Interfaces

• Object Interfaces are used to define the shape or structure of an object.
• They define the properties with the types that an object should contain.
• We use the 'interface' keyword to declare an object interface followed by the interface name and its properties.
• They can be implemented by other interfaces and classes, promoting code reusability and maintainability.

Example: This example shows the use of the TypeScript Interfaces.

interface Employee {
    eid: string,
    name: string
}
const emp: Employee = {
    eid: "E54321",
    name: "Ravi"
};

console.log(emp);

Output:

{ eid: 'E54321', name: 'Ravi' }

Intersections

• Intersections allow us to combine multiple types into a single type.
• We use the '&' operator to merge all properties and methods of each type involved.
• Intersections are used to compose multiple types by merging existing types or interfaces.

Example: This example shows the use of TypeScript intersections

interface Employee {
    eid: string,
    name: string
}
interface Address {
    street: string;
    city: string;
}

type EmployeeWithAddress = 
    Employee & Address;

const employeeWithAddress: 
    EmployeeWithAddress = {
    eid: "E54321",
    name: "Bob",
    street: "123 BHU Lanka",
    city: "Varanasi",
};

console.log(employeeWithAddress);

Output:

{
  eid: 'E54321',
  name: 'Bob',
  street: '123 BHU Lanka',
  city: 'Varanasi'
}

Object Interfaces vs. Intersections:

Conclusion: TypeScript object interfaces are used to define the structure of individual objects, while intersections combine multiple types to create new composite types. In many cases, we might use both object interfaces and intersections depending on the specific requirements of our applications. Understanding when and how to use these powerful features is essential for building robust applications using TypeScript.