The State of CSS-in-JS: Styled-Components vs. Emotion

Emotion and styled-components have similar syntax, but Emotion supports css prop and object style writing, which is more suitable for dynamic scenarios; 2. Emotion has better performance, smaller packaging volume, and lighter SSR; 3. Both support themes, but the styled-components ecosystem is more mature and has exclusive DevTools; 4. Emotion maintenance is more stable, TypeScript support is better, and community trends are more recommended; 5. It is recommended to choose Emotion for new projects, especially when paying attention to performance and long-term maintenance, while styled-components is suitable for projects that already have ecosystems or rely on their debugging tools, but in the long run, you can consider turning to atomization or compile-time style solutions.

CSS-in-JS was once considered the "future" of processing styles in the React ecosystem. It writes CSS into JavaScript, allowing styles to have scope isolation, dynamic generation and theme support capabilities. Nowadays, although its popularity has declined, styled-components and Emotion are still the two most mainstream choices. If you are struggling with which one to use in your project, this article will help you clarify the key differences and applicable scenarios.

1. The syntax and development experience are almost the same

Both use template string syntax to write CSS, and the API design is also highly similar, and the cost of getting started is very low.

 // styled-components
const Button = styled.button`
  background: ${props => props.primary ? 'blue' : 'gray'};
  padding: 10px;
`;

// Emotion (using styled API)
const Button = styled.button`
  background: ${props => props.primary ? 'blue' : 'gray'};
  padding: 10px;
`;

Emotion actually implements most of the APIs of styled-components, so many projects migrate from styled-components to Emotion, and the code is almost unnecessary to change.

But Emotion also provides more flexible css prop and object style writing, suitable for more dynamic scenarios:

 /** Emotion-specific css prop */
<div css={{ color: &#39;red&#39;, fontSize: 16 }} />

/** or pass in css template*/
<div css={css`color: red;`} />

This writing method is particularly convenient when it is necessary to temporarily overwrite styles or write logical styles inside components, while styled-components is not natively supported.

2. Performance: Emotion is faster and packed smaller

In terms of performance, Emotion usually wins .

• Runtime Performance : Emotion uses more efficient caching and injection mechanisms, and style generation and updates are faster.
• Packaging volume : Emotion's core package is smaller, especially when using @emotion/css instead of @emotion/styled , it can be introduced on demand.
• Server-side rendering (SSR) : Both are supported, but Emotion's SSR injection is lighter and the generated <style></style> tags are more compact.

Community benchmarks (such as styled-components-perf ) show that Emotion consumes less memory when rendering a large number of components and renders the first screen faster.

3. Topic and toolchain support

Both support theme passes (via ThemeProvider ), but the implementation is slightly different.

• styled-components : Theme is one of its core selling points, with mature ecosystems, and supporting documents and third-party libraries (such as polished) are popularized earlier.
• Emotion : It also supports ThemeProvider and can coexist with the theme of styled-components (because the API is consistent), but the community resources are slightly less.

Development tools:

• styled-components has a dedicated DevTools browser plug-in, which can directly view the style blocks corresponding to the components, making it easy to debug.
• Emotion does not have independent DevTools, but can be debugged through class name prefix or source code mapping, and the experience is slightly weak.

4. Community and Maintenance Status

• styled-components was once synonymous with CSS-in-JS and was very active in 2016–2020, but in recent years the update has slowed down and the maintenance pace is unstable.
• Emotion is actually used by teams such as Google and GitHub. It has more continuous maintenance, clear documentation, and better support for TypeScript.

In addition, with the rise of "zero runtime" solutions such as Tailwind CSS and Vanilla Extract , the overall usage of CSS-in-JS is declining. But if you insist on using CSS-in-JS, Emotion has gradually become a more recommended choice due to its flexibility and performance.

Summary: Which one should I choose?

• ✅ Choose Emotion if you :

  • Focus on performance and packaging volume
  • Need to write inline styles of css prop
  • Hopefully better TypeScript support
  • The project is maintained for a long time and requires stable maintenance

• ✅Select styled-components if you :

  • The team is already familiar with it, and the migration costs are high
  • DevTools Depend on it
  • Used a lot of third-party UI libraries based on it

But to be honest, if you want to use CSS-in-JS for new projects now, Emotion is a more modern and efficient choice . In the long run, you can also consider gradually turning to atomized CSS (such as Tailwind) or compile-time style solutions.

Basically all this is not complicated but easy to ignore.

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