CSS Modules vs styled-components: What are the differences?

Introduction

CSS Modules and styled-components are two popular approaches for styling web applications. While both serve the same purpose of styling components, there are key differences between the two. In this article, we will explore and compare these differences.

1. File Structure and Separation of Concerns: With CSS Modules, styles are defined in separate CSS files, allowing for a clear separation between HTML markup and styling logic. This helps maintain a structured file organization and promotes a better understanding of the application's architecture. On the other hand, styled-components encapsulate styles within the component itself, eliminating the need for separate CSS files. This provides a more self-contained and modular approach to styling.

2. CSS Class vs Component-Level Styling: CSS Modules use traditional CSS classes to apply styles to elements. Each class is unique and can be applied to any element within the HTML markup. Styled-components, on the other hand, generate unique class names under the hood and associate them directly with the component. This ensures that styles are applied only to the specific component and its descendants, preventing unwanted style conflicts.

3. Dynamic Styling: CSS Modules support dynamic styling by using JavaScript to manipulate classes and apply styles conditionally. By changing the class name dynamically, different styles can be applied to elements based on specific conditions or user interactions. In contrast, styled-components provide a more convenient way to handle dynamic styling by allowing components to accept props. These props can then be used inside the component's styling rules, providing a more concise and intuitive approach to dynamic styling.

4. Style Inheritance and Composition: CSS Modules do not natively support style inheritance or composition. However, this can be achieved through the use of CSS preprocessors like Sass or Less. In styled-components, style inheritance and composition are built-in features. Components can inherit styles from other components, and styles can be composed together to create new variations or combinations.

5. Developer Experience: CSS Modules provide a familiar development experience for CSS developers. There is no additional learning curve, and existing CSS skills can be easily applied. On the other hand, styled-components introduce a new way of writing styles by using JavaScript tagged template literals. This may require some initial learning and adjustment for developers who are not familiar with this approach.

6. Tooling and Ecosystem: CSS Modules have been around for a longer time and have a mature ecosystem around them. There are various build tools and integrations available specifically for CSS Modules, making it easier to integrate them into existing projects. Styled-components, although relatively newer, has gained popularity and has its own ecosystem. However, it may require additional configuration and setup compared to CSS Modules.

In summary, CSS Modules and styled-components have key differences in terms of file structure, component-level styling, dynamic styling, style inheritance and composition, developer experience, and tooling/ecosystem. Each approach has its own strengths and considerations, and the choice between them depends on factors such as project requirements, team preferences, and existing codebase.