Understanding generic types in Typescript

As a developer, you may have encountered situations where you need to create reusable code that can work with different data types. This is where TypeScript's generic types come in handy. In this article, we will take a closer look at generic types and how they can help you write more flexible and reusable code.

What are Generic Types in TypeScript?

Generic types in TypeScript allow you to create functions, classes, and interfaces that can work with different types of data. They are essentially placeholders that can be replaced with actual types when the code is used.

export type TEntity = {
  email: string;
  age: number;
}

const myEntity: TEntity = {
  email: "[email protected]",
  age: 25,
};

// const withValidation = (entity: TEntity) => { // with type
const withValidation = <T>(entity: T) => { // with generic types
  return {
    ...entity,
    validate() {
      console.log("Validating");
    },
  };
};

const newMyEntity = withValidation(myEntity);
// we see a new method in autocomplete by typescript
newMyEntity.validate();

Using the sample code above, we can see that TEntity is a generic type that defines the form of an entity object. It has two properties, email of type string and age of type number. This allows us to define the shape of the object without specifying the actual values.

The withValidation function is another example of a generic type. It takes a generic type T, which can be any type, and returns an object that contains the properties of the original entity as well as a validate function.

Pros

1. Reusability and Flexibility: By using generic types, you can create functions, classes, and interfaces that can be used with different data types so you don't need to rewrite code for each type.
2. Type safety: TypeScript provides type safety for generic types. This means that the compiler catches any errors before runtime, making it easier to write and debug code.

Cons

1. Complexity: Generic types can make code more complex and harder to read. It can be difficult to understand the meaning of the code when generic types are used extensively.
2. Learning curve: It can take some time to understand and learn how to use generic types effectively. Developers unfamiliar with generic types may find it difficult to understand code that uses them.

Summary

Generic types in TypeScript allow you to create reusable and flexible code that can work with different data types. They provide type safety and make it easier to write and debug code. However, they can also make code more complex and harder to read, and there is a learning curve associated with using them effectively.
In summary, understanding and using generic types can greatly improve the quality of your code, making it more efficient and reusable. Now that you know the pros and cons of using generic types in TypeScript, you can decide if they are the right choice for your development needs.