As developers, we all strive for a well-organized codebase that is easy to navigate and maintain. One crucial aspect of organizing code is effectively managing types. In this article, we will explore some best practices for organizing types in your application code, helping you simplify and streamline your development process.

Group Types with Related Code

When it comes to organizing types, it's beneficial to keep them closely associated with the code they describe. By colocating types with the related implementation code, you can easily understand and modify both aspects of the code in one place. This approach enhances code readability and reduces the cognitive load of jumping between different files.

For example, if you have a JavaScript component called MyComponent that requires specific props, it's recommended to define the types directly within the same file:

// MyComponent.ts

interface Props {
  foo: string,
  bar: number
}

/**
 * MyComponent is a reusable component.
 * @param {Props} props - The component props.
 */
export const MyComponent = (props: Props) => {
  // Component implementation
};

By colocating the type definition within the component file, you can easily refer to the type while working on the implementation. This approach ensures that the code remains self-contained and intuitive to work with.

Extract Shared Types to a Separate Module

While colocating types with their associated code is beneficial for single-use types, it may become impractical when multiple components or modules share the same types. In such cases, it's advisable to extract the shared types into a separate module.

Create a dedicated module or file that houses the shared types, and import them wherever they are needed. This approach ensures consistency across your codebase and reduces duplication of type definitions.

For instance, consider a scenario where multiple components within your application require the same set of props. Instead of duplicating the type definitions in each component file, extract the shared types into a separate module:

// components.types.ts

/**
 * @typedef {object} Props
 * @property {string} foo - The foo property.
 * @property {number} bar - The bar property.
 */
interface Props {
  foo: string,
  bar: number
}

export { Props };

Now, you can easily import the shared types in any component file that requires them:

// MyComponent.js
import { Props } from './components.types.ts';

/**
 * @param {Props} props - The component props.
 */
const MyComponent = (props: Props) => {
  // Component implementation
};

By centralizing shared types in a separate module, you promote code reuse, simplify maintenance, and ensure consistent type definitions throughout your application.

Leverage Folder Structure for Type Organization

In addition to colocating types and extracting shared ones, you can further enhance your codebase organization by leveraging your folder structure. By organizing your types based on their usage and scope, you can intuitively locate and manage them.

For instance, you can create a dedicated folder within your project structure to hold type-related files:

|- src
  |- components
    |- MyComponent.ts
  |- types
    |- components.types.ts

By following this approach, you can keep the types directly associated with the components they describe. This way, when working on a specific component, you know exactly where to find its corresponding types.

Additionally, if your application consists of multiple packages or modules, consider creating a separate package or module solely for shared types. This allows you to centralize and manage shared types efficiently, ensuring consistency across different parts of your codebase.

Conclusion

Organizing types effectively is crucial for maintaining a clean and understandable codebase. By colocating types with related code, extracting shared types to separate modules, and leveraging your folder structure, you can simplify your development process and improve code maintainability.

Remember, the goal is to strike a balance between keeping types close to their implementation and avoiding unnecessary duplication. Apply these best practices to your codebase and tailor them to suit your specific project requirements. Happy coding!

References: TotalTypeScript