Explore TypeScript types and interfaces | by José Granja | September 2023

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Let’s take a deep dive into the nuances of types and interfaces

When working with TypeScript, developers often make a crucial decision: to use type aliases or interfaces to define data structures and contracts. Both types and interfaces serve distinct purposes and offer unique features and use cases that can significantly impact the readability, maintainability, and compatibility of your code.

In this comprehensive guide, we dive deeper into the nuances of TypeScript’s types and interfaces while exploring real-world examples highlighting differences in behavior, implementation, and best practices. At the end of this exploration, you will be able to make informed decisions about whether to leverage the flexibility of type aliases or the strict enforcement of interface contracts to maximize the success of your projects TypeScript.

Let’s start by looking at an appropriate definition.

Type aliases

Type aliases are a powerful tool for creating complex and precise type definitions. With type aliases, developers can create complex unions, intersections, and mapped types to improve code expressiveness. These aliases are particularly suitable for scenarios requiring versatile and adaptable types because they provide the flexibility to merge different types into a single, coherent structure. By leveraging type aliases, developers can achieve streamlined type definitions that perfectly align with dynamic application requirements.

type Planet = {
hasLife: boolean;
numberOfMoons: number;
}

Interfaces

Interfaces, on the other hand, excel at creating contracts that classes must adhere to. The rigid structure of interfaces ensures a consistent model that enforces property names, types, and method signatures across all implementation classes. This rigor improves code predictability and reduces the risk of runtime errors, making interfaces the go-to choice when designing APIs or ensuring class consistency. Interfaces facilitate the development of robust, well-documented components, which is particularly beneficial in collaborative environments.

interface Planet {
hasLife: boolean;
numberOfMoons: number;
}