CSS Modules vs Emotion: What are the differences?

Key differences between CSS Modules and Emotion

CSS Modules and Emotion are both popular libraries used for styling in web development. While they share some similarities, there are several key differences that set them apart.

1. Importing Styles: When using CSS Modules, styles are imported as regular JavaScript objects. This means that styles are locally scoped to the component they are imported into, preventing class name collisions. On the other hand, Emotion uses a different approach where styles are written using tagged template literals. This allows for more flexibility in composing and reusing styles, but it also means that styles are not locally scoped by default.

2. Style Composition: CSS Modules support the concept of composing styles by using composition syntax. This means that you can easily combine multiple styles together to create new styles. Emotion, on the other hand, has a different way of handling style composition. It provides a set of utility functions that can be used to combine styles, allowing for more fine-grained control over how styles are composed.

3. Dynamic Styling: CSS Modules primarily focus on static styles that are defined at build time. While it is possible to add dynamic styling using JavaScript, it requires additional configuration and complexity. Emotion, on the other hand, is designed with dynamic styling in mind. It provides powerful features like styled components and CSS-in-JS syntax that make it easier to create dynamic and interactive styles.

4. Code Size and Performance: CSS Modules generate class names at build time, which can result in larger bundle sizes if many classes are used. However, it typically offers better runtime performance since the styles are applied using regular CSS classes. Emotion, on the other hand, generates styles at runtime, which can result in smaller bundle sizes. However, this can lead to slightly slower runtime performance due to the additional overhead of generating and applying styles.

5. Developer Experience: CSS Modules fit well with the traditional CSS workflow and can be easier to adopt for developers who are already familiar with CSS. Emotion, on the other hand, provides a more flexible and powerful API with features like theming, prop-based styling, and dynamic styles. This can make it more suitable for complex styling requirements and developers who prefer a more declarative approach.

6. Community and Ecosystem: CSS Modules has been around for a longer time and has a larger community and ecosystem. It is well-supported by popular build tools and frameworks like webpack and React. Emotion, on the other hand, is a more recent library but has gained popularity due to its powerful features and developer-friendly APIs. It has a growing community and is actively maintained.

In Summary, CSS Modules and Emotion differ in how styles are imported, composed, and used for dynamic styling. CSS Modules offer a simpler and more traditional CSS workflow, while Emotion provides more flexible and powerful styling options. The choice between the two depends on the specific project requirements and developer preferences.