CSS-in-JS: A Deep Dive into Styled Components vs Emotion

As the modern web evolves, the conversation around styling methodologies continues to gain momentum. In recent years, the CSS-in-JS pattern has emerged as a compelling solution for styling in JavaScript applications. Among the several libraries available, Styled Components and Emotion have become the go-to options for many developers. This article aims to provide a comprehensive comparison of these two libraries, highlighting their strengths, weaknesses, and practical examples to help you make an informed decision.

What is CSS-in-JS?

CSS-in-JS refers to a styling technique where CSS is composed using JavaScript. This allows developers to encapsulate styles at the component level, making it easier to manage styles in large applications that use frameworks like React. By using CSS-in-JS, developers can take advantage of JavaScript’s capabilities, such as conditional styles, theme management, and dynamic styling based on props.

Overview of Styled Components

Styled Components is a library that allows you to use component-level styles in your React applications. It utilizes tagged template literals to define styles, enabling a clean and intuitive way to create styled components.

Key Features of Styled Components

• Tagged Template Literals: Write plain CSS within JavaScript functions.
• Theming: Integrated theming support using the ThemeProvider.
• Dynamic Styles: Easily create responsive styles based on props.
• Automatic Vendor Prefixing: Handles browser compatibility issues internally.

Example of Styled Components

Here’s a simple example showcasing how to implement styled components:

import styled from 'styled-components';

const Button = styled.button`
  background-color: ${(props) => props.primary ? 'blue' : 'gray'};
  color: white;
  padding: 10px 15px;
  border: none;
  border-radius: 4px;
  cursor: pointer;

  &:hover {
    opacity: 0.8;
  }
`;

// Usage
Primary Button
Default Button

Overview of Emotion

Emotion is another powerful CSS-in-JS library that makes styling components easy and performant. It offers a similar approach to Styled Components but comes with additional flexibility.

Key Features of Emotion

• Styled API and CSS Prop: Supports both a styled-components-like syntax and a css prop for inline styles.
• Interpolation: Provides extensive capabilities for dynamic styling.
• Performance: Optimized for performance with a focus on minimizing runtime CSS generation.
• Server-Side Rendering: Supports server-side rendering, allowing for better performance and SEO.

Example of Emotion

This example illustrates how to create styled components using the Emotion library:

/** @jsxImportSource @emotion/react */
import { css } from '@emotion/react';

const buttonStyle = (primary) => css`
  background-color: ${primary ? 'blue' : 'gray'};
  color: white;
  padding: 10px 15px;
  border: none;
  border-radius: 4px;
  cursor: pointer;

  &:hover {
      opacity: 0.8;
  }
`;

// Usage
Primary Button
Default Button

Comparison: Styled Components vs Emotion

Both Styled Components and Emotion offer robust solutions for writing styles in JavaScript, but they do have some distinct differences. Let’s break it down:

1. Syntax and Usage

Styled Components utilize a tagged template literal syntax that feels very natural if you are already accustomed to writing CSS. Emotion, on the other hand, provides two approaches: the styled API similar to Styled Components and a `css` prop for more flexibility.

If you prefer a CSS-in-JS style that remains close to traditional CSS, Styled Components may be your best choice. If you appreciate flexibility in approach and syntax, you might lean towards Emotion.

2. Dynamic Styling

Both libraries support dynamic styling down to component levels, but while Styled Components make this via prop functions, Emotion introduces an interpolation syntax that allows for more complex styles in a more concise manner. This can be particularly useful when styling multiple elements based on dynamic props.

3. Performance

Emotion is designed with performance in mind, particularly when it comes to runtime performance. It generates the CSS at build time, leading to more optimized bundles. Styled Components, while efficient, may not match the raw speed of Emotion in complex applications. If performance is a critical factor for your application, testing both can yield helpful results.

4. Theming and Global Styles

Both libraries offer theming capabilities, but Styled Components’ ThemeProvider is more commonly praised for its straightforward implementations. Emotion has its own theming capabilities but may require more setup for some use cases.

5. Community and Ecosystem

Styled Components is widely adopted in the React community and has a robust ecosystem of plugins and extensions. Emotion also has a growing community, boasting integrations with popular frameworks and libraries. If community support and third-party tools are essential, Styled Components may have the edge.

When to Use Which?

Deciding whether to use Styled Components or Emotion largely depends on the specific needs of your project and team preferences:

• Choose Styled Components if:
• You prefer a syntax that closely resembles traditional CSS.
• You need comprehensive theming support.
• You want strong community support with plenty of examples and resources.
• Choose Emotion if:
• You need maximum flexibility with styling options.
• You are building complex applications that require optimal performance.
• You want the freedom to mix and match styled components and styled props.

Conclusion

Both Styled Components and Emotion provide robust solutions for styling in JavaScript applications. Ultimately, the choice between the two will depend on your team’s coding style, application requirements, and long-term planning for maintainability and performance.

By understanding the capabilities and limitations of each library, you’ll be better equipped to select the one that best meets your needs. Experimenting with both can also provide valuable insights into your styling preferences and application scales.

As the landscape of CSS-in-JS libraries continues to evolve, keeping informed about the latest developments and community practices will help you make better development choices. Happy coding!