Styling React Components: A Comparison of CSS in JS, Styled Components, and Emotion

React is a popular JavaScript library for building UI components. One of the essential aspects of UI components is styling. In this article, we will discuss three popular approaches to styling React components – CSS in JS, Styled Components, and Emotion – and their pros and cons.

1. CSS in JS

CSS in JS is an approach that allows you to write CSS directly within JavaScript files. In a React application, this means writing our CSS within our React components.

Pros

Component Scope: CSS is applied only to the component it's defined in, avoiding global scope issues.
Dynamic Styling: Easily set styles based on component props or state – no need for CSS pre-processors like Sass or Less.
JS Power: Access JavaScript's full capabilities, such as variables, functions, and conditional statements.

Cons

Verbosity: Writing CSS in JavaScript can be more verbose than traditional CSS.
Learning Curve: Developers need to learn a new syntax and best practices for structuring CSS within JavaScript.

2. Styled Components

Styled Components is a popular library for styling React components using tagged template literals. It allows you to write traditional CSS syntax while still taking advantage of the benefits of CSS in JS.

Pros

Ease of Use: Styled Components' syntax closely resembles traditional CSS, making it easy to use for developers familiar with CSS.
Dynamic Styling: Similar to CSS in JS, Styled Components can accept props to create dynamic styles.
Automatic Vendor Prefixing: Automatically adds vendor prefixes for improved browser compatibility.
Server-Side Rendering Support: Styled Components can be rendered on the server, ensuring consistent styles across client and server.

Cons

Additional Dependency: Requires adding an extra library to your project.
Performance Concerns: Though generally performant, Styled Components can be slower than other methods in some cases.

3. Emotion

Emotion is another CSS in JS library that combines the best of Styled Components and inline CSS in JS. Emotion offers two main APIs - styled and css.

Pros

Flexibility: Provides both the Styled Components API and a more traditional CSS in JS API (using the css prop).
Performance: Emotion is optimized for performance, making it faster than Styled Components in many cases.
Server-Side Rendering Support: Like Styled Components, Emotion supports server-side rendering.
Automatic Vendor Prefixing: Emotion also handles vendor prefixes automatically.

Cons

Additional Dependency: Like Styled Components, Emotion requires adding an extra library to your project.
Learning Curve: Developers may need to learn both APIs to take full advantage of Emotion's features.

Conclusion

Each of these approaches to styling React components has its advantages and drawbacks. When choosing the best method for your project, consider factors such as your team's familiarity with CSS, your project's performance requirements, and whether server-side rendering is necessary. Ultimately, the best approach depends on your specific needs and preferences.