CSS-in-JS Solutions: A Practical Comparison of styled-components and emotion

Definition

CSS-in-JS has become a popular approach for managing styles in modern web development. It offers a way to encapsulate styles within JavaScript components, which can help improve maintainability, eliminate global styles, and enable dynamic theming. In this section, we’ll compare two prominent CSS-in-JS libraries: styled-components and emotion. We’ll discuss the strengths and weaknesses of each, explore when to use them effectively, and delve into performance considerations.

Introduction to styled-components and emotion

styled-components

Styled-components is a popular CSS-in-JS library that allows you to write actual CSS in your JavaScript code using tagged template literals. It aims to improve the component-based approach to styling by encapsulating styles within individual components. This approach provides a clear separation of concerns and makes it easier to maintain and reason about styles.

Here’s a simple example of using styled-components to style a React component:

import styled from 'styled-components';

const Button = styled.button`
  background-color: ${props => props.primary ? 'blue' : 'white'};
  color: ${props => props.primary ? 'white' : 'blue'};
  border: 2px solid blue;
  padding: 0.5em 1em;
`;

// Usage
<Button primary>Primary Button</Button>
<Button>Secondary Button</Button>

emotion

Emotion is another popular CSS-in-JS library that focuses on performance and flexibility. It provides powerful tools for creating styled components and managing styles. Emotion leverages a runtime to generate unique class names for styles, which can be beneficial for performance and server-side rendering (SSR).

Here’s an example of using emotion to style a React component:

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

const buttonStyles = css`
  background-color: ${props => props.primary ? 'blue' : 'white'};
  color: ${props => props.primary ? 'white' : 'blue'};
  border: 2px solid blue;
  padding: 0.5em 1em;
`;

// Usage
<button css={buttonStyles}>Primary Button</button>

Comparison: styled-components vs. emotion

Both styled-components and emotion have their strengths and use cases. Let’s compare them across several important aspects:

Ease of Use and Syntax

styled-components offers a clean and intuitive syntax that closely resembles CSS. This can make it easier for designers and developers familiar with CSS to jump in and start using it. The tagged template literals provide a readable way to define styles.

emotion, on the other hand, allows you to use the familiar CSS syntax with the css function. This can be advantageous if you prefer the standard CSS syntax and want to keep your stylesheets consistent.

Theming and Global Styles

styled-components has excellent support for theming out of the box. You can define theme variables and easily access them within your styled components. This makes it convenient to create consistent designs.

emotion also supports theming but requires a bit more setup. It provides a ThemeContext that you can use to pass theme variables down the component tree.

For global styles, styled-components provides a createGlobalStyle utility that lets you define global styles, such as resetting default browser styles.

Performance

When it comes to performance, emotion has a slight edge due to its class name generation approach. It assigns unique class names at runtime, which can help with SSR and avoid style collisions.

styled-components also performs well in most cases, but its generated class names are based on component names and may not be as efficient as emotion’s approach, especially for larger applications.

When to Use Each Library

• Use styled-components if you value a clean and intuitive syntax, and if theming is a crucial aspect of your project.

• Use emotion if you prioritize performance, particularly for SSR scenarios, and if you prefer to stick with the traditional CSS syntax.

Conclusion

Both styled-components and emotion are powerful CSS-in-JS libraries with their own unique features and benefits. The choice between them depends on your specific project requirements and personal preferences. Consider the ease of use, theming capabilities, and performance considerations when deciding which library to use in your application. Whichever you choose, CSS-in-JS can greatly enhance the maintainability and scalability of your styles in modern web development.

Thanks for reading, see you in the next one!