Creación y uso de interfaces de TypeScript

The implementation of interfaces in TypeScript represents a powerful tool that, although it may initially appear complex, offers extraordinary flexibility in application development. Interfaces allow you to define data structures and behaviors that can be easily reused, creating more maintainable and scalable code. Let's discover how to take advantage of this fundamental feature of the language to improve our projects.

What are interfaces in TypeScript and why are they so flexible?

Interfaces in TypeScript are contracts that define the structure that an object or function should have. Unlike classes, interfaces can be more easily extended and transferred between different files, which makes them extremely versatile.

One of the main advantages of interfaces is that they allow defining both properties and methods, providing a complete way of modeling objects and behaviors. This feature makes them ideal tools for creating reusable and well-structured code.

To implement a basic interface in TypeScript, we use the reserved word interface followed by the name we want to assign to it:

interface Person { name: string; age: number; isDeveloper: boolean;}

This interface defines that any object of type Person must have three properties: name (string), age (number) and isDeveloper (boolean).

How to use interfaces for individual objects?

Once an interface is defined, we can create objects that implement it. This ensures that these objects comply with the defined structure:

let person: Person = { name: "John", age: 30, isDeveloper: true};
console.log(person);

When executing this code, we will see in the console the object with the defined properties. TypeScript will check at compile time that the object complies with the interface structure, which helps prevent errors.

How to work with collections of interfaces?

Interfaces can also be used to define arrays of objects that share the same structure:

let people: Person[] = [ { { name: "John", age: 30, isDeveloper: true }, { name: "Mary", age: 25, isDeveloper: false }];
console.log(people);

This code creates an array of objects that implement the Person interface. When executed, we will see in the console all the elements of the array.

How to define methods in interfaces?

A powerful feature of interfaces is the ability to define methods that must be implemented by the objects that use them:

interface Sumar { sum(a: number, b: number): number;} }
let sum: Sumar = { sum(a: number, b: number): number { return a + b; } } };
console.log(sum.sum(3, 5)); // Result: 8.

In this example, the Sum interface defines a method called sum that receives two numeric parameters and returns a number. Then, we create an object that implements this interface by providing the implementation of the method.

Why use interfaces for methods?

Although it may seem a bit bureaucratic to define methods through interfaces, this practice offers several advantages:

1. Consistency: It ensures that all objects that implement the interface have the same methods with the same signatures.
2. Documentation: Interfaces act as clear documentation of what is expected of an object.
3. Flexibility: Different classes or objects can implement the same interface in different ways.

How to combine properties and methods in interfaces?

One of the great advantages of interfaces in TypeScript is that they can combine both properties and methods in the same definition:

interface Person { name: string; age: number; isDeveloper: boolean; describe(): string; isMayor(): boolean;}

This interface defines not only the properties of a person, but also methods that can provide additional information about it. This ability to combine properties and behaviors makes interfaces extremely versatile tools.

Interfaces in TypeScript are fundamental tools that allow you to create more structured, reusable, and maintainable code. Although they may seem complex at first, once you understand how they work, they become indispensable allies in the development of robust applications. Have you used interfaces in your projects? Share your experience and how they have improved your code in the comments.