Emotion - Styling | Awesome React

Why Emotion?

Emotion stands out in the CSS-in-JS ecosystem by providing developers with unparalleled flexibility. It is not tied to a single styling paradigm; instead, it offers multiple APIs—including a styled component API similar to styled-components and a css prop for inline-style objects—allowing teams to choose the approach that best fits their workflow. This flexibility, combined with a strong focus on performance and developer experience, makes it a compelling choice for modern web applications.

Framework Agnostic: While popular in the React ecosystem, Emotion's core is framework-agnostic, making it adaptable to different environments.
Performance: Emotion is architected for speed. It offers a zero-runtime static extraction option with a Babel plugin, which pre-compiles styles at build time, eliminating runtime overhead.
Flexible APIs: Developers can use the popular styled API for creating styled components or the css prop for applying styles directly to elements, which feels like a super-powered style attribute.
Developer Experience: With features like source maps and a dedicated ESLint plugin, Emotion makes debugging and maintaining styles straightforward and predictable.
Server-Side Rendering (SSR): It provides an efficient and easy-to-configure solution for server-side rendering, which is critical for performance and SEO in many applications.

Emotion is ideal for projects that demand high performance and where developers may have different preferences for writing styles.

Code Snippet

This example demonstrates two of Emotion's core patterns: the styled API and the css prop. Both achieve a similar outcome, showcasing the library's flexibility.

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

// 1. Using the `styled` API to create a component
const StyledButton = styled.button`
  color: turquoise;
  background-color: #282c34;
  font-size: 1.2rem;
  padding: 10px 15px;
  border: 1px solid turquoise;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.3s ease;

  &:hover {
    color: #282c34;
    background-color: turquoise;
  }
`;

// 2. Using the `css` prop for instance-specific styles
function App() {
  const specialTextStyle = css`
    font-weight: bold;
    color: hotpink;
  `;

  return (
    <div>
      <StyledButton>Styled API Button</StyledButton>
      <button
        css={css`
          margin-left: 10px;
          color: white;
          background-color: hotpink;
          /* You can also compose styles */
          ${specialTextStyle}
        `}
      >
        CSS Prop Button
      </button>
    </div>
  );
}

export default App;

This snippet shows how styled creates a reusable, styled element, while the css prop is used for applying styles directly and composing them, offering both structure and flexibility.

Pros and Cons

No library is perfect; understanding the trade-offs is key to selecting the right tool.

Pros

API Flexibility: The choice between the styled API and the css prop allows teams to adopt the patterns that best suit their needs.
Excellent Performance: With its zero-runtime capabilities and efficient style extraction for SSR, Emotion is one of the fastest CSS-in-JS libraries.
Great Developer Tools: Source maps make debugging styles in browser developer tools a seamless experience, mapping generated classes back to the source code.

Cons

Potential for Inconsistency: The flexibility of multiple APIs can lead to inconsistent styling patterns within a team if no clear convention is established.
Configuration Overhead: To unlock its full performance potential (like zero-runtime), some initial Babel and ESLint plugin configuration is required.
Slightly Smaller Community: While very popular, its community is smaller than that of styled-components, which can sometimes mean fewer third-party tools or community-contributed examples.

Comparison with Other Styling Libraries

The table below outlines the positioning differences between Emotion and other popular Styling libraries to help you make an informed decision:

Library	Design Philosophy	Best For	Pain Points
Emotion	CSS-in-JS Flexible CSS-in-JS with multiple patterns (template literals, objects) and a framework-agnostic core.	Flexible Styling Teams that want both object and string styles and solid SSR support.	Multiple APIs The flexibility can lead to inconsistent usage patterns across a team.
Styled Components	CSS-in-JS Component-based styling where CSS is written in tagged template literals.	Dynamic & Themed UIs When styles need to adapt heavily to props or a global theme.	Runtime Overhead Can introduce a slight performance cost due to style computation at runtime.
Tailwind CSS	Utility-First Applies styles via pre-built classes directly in markup.	Custom Designs Projects that need a bespoke UI without the constraints of a component library.	Verbose HTML Can lead to cluttered markup if not managed with components.

Verdict: When to Adopt

Adopt Emotion when you need a high-performance, flexible CSS-in-JS solution. It's a fantastic choice for teams that may include developers with different styling preferences (e.g., some prefer objects, others prefer strings) or for projects where performance is a top priority and the team is willing to configure build tools to enable zero-runtime extraction. Its robust support for server-side rendering also makes it a go-to for modern frameworks like Next.js where initial page load performance is critical.

TL;DR