CSS-in-JS is a modern way of styling web applications. Instead of writing CSS in separate files, developers write styles directly inside JavaScript or TypeScript code. This method helps keep styles close to the components they belong to. Over the years, many CSS-in-JS libraries have been created. Three popular ones are Emotion, Stitches, and Vanilla Extract.
In this blog, we will look at what makes these libraries different and how they help in building better web applications. If you are learning web development in full stack developer classes, understanding CSS-in-JS is important. It is commonly used in React projects and can help make your apps cleaner and easier to maintain.
What is CSS-in-JS?
CSS-in-JS means writing CSS styles within your JavaScript or TypeScript files. This approach lets you style components directly, without switching between different files. It also allows the use of variables, logic, and themes in your styles.
For example, instead of writing this in a .css file:
.button {
  background-color: blue;
  color: white;
}
You can write it like this in a JavaScript file:
const buttonStyle = {
  backgroundColor: ‘blue’,
  color: ‘white’,
}
Many developers learn this technique through full stack developer classes, as it is now a common practice in frontend development.
Why Use CSS-in-JS?
There are many reasons why developers like CSS-in-JS:
- Scoped styles: Styles are tied to specific components, so they don’t affect other parts of the app.
- Dynamic styles: You can use JavaScript logic to create different styles based on props or state.
- Easier maintenance: Since styles are next to your components, it’s easier to find and update them.
- Theme support: Libraries often make it easy to switch themes or support dark mode.
With more teams building apps with React and other frameworks, CSS-in-JS helps improve the development process. These topics are usually covered in a full stack course, where students get to use modern tools and libraries in real-world projects.
Emotion
Emotion is one of the most favoured CSS-in-JS libraries. It is known for being flexible, powerful, and easy to use. You can write styles using two different methods in Emotion:
- Styled components
- The css prop or function
Example using styled components
/** @jsxImportSource @emotion/react */
import styled from ‘@emotion/styled’
const Button = styled.button`
  background-color: blue;
  color: white;
`
Example using css prop
/** @jsxImportSource @emotion/react */
import { css } from ‘@emotion/react’
const buttonStyle = css`
  background-color: blue;
  color: white;
`
Emotion is fast and has great support for theming and animations. It also works well with TypeScript. This makes it a good choice for both small and large projects.
Many students in full stack developer classes use Emotion in their first React apps because it feels natural and is well-documented.
Stitches
Stitches is a newer library but has gained popularity quickly. It focuses on performance, type safety, and developer experience. Stitches is written in TypeScript, so it works very well in TypeScript projects.
One of the key features of Stitches is its support for tokens and theming out of the box. This means you can define your colors, fonts, and sizes once and use them everywhere in your app.
Example in Stitches
import { createStitches } from ‘@stitches/react’
const { styled } = createStitches({
  theme: {
    colors: {
      primary: ‘blue’,
      text: ‘white’,
    },
  },
})
const Button = styled(‘button’, {
  backgroundColor: ‘$primary’,
  color: ‘$text’,
})
Stitches encourages clean and organized styling. It is also very fast, with low runtime cost.
For developers learning in a full stack course, Stitches is often introduced alongside other tools like Next.js and TypeScript. This helps learners understand how to build scalable and well-structured applications.
Vanilla Extract
Vanilla Extract is different from Emotion and Stitches. It is a zero-runtime CSS-in-TypeScript library. This means all styles are compiled at build time, and no style logic runs in the browser. This leads to better performance and smaller bundle sizes.
Instead of styling components directly in your JSX files, Vanilla Extract lets you write styles in .css.ts files. These styles are still written in TypeScript, but they are separate from your components.
Example in Vanilla Extract
// button.css.ts
import { style } from ‘@vanilla-extract/css’
export const button = style({
  backgroundColor: ‘blue’,
  color: ‘white’,
})
Using it in a component
import * as styles from ‘./button.css’
function Button() {
  return <button className={styles.button}>Click me</button>
}
Vanilla Extract gives you the benefits of type safety and scoped styles, without adding any runtime cost. It’s a good choice for performance-focused projects.
Though it’s slightly more complex than the others, some full stack developer classes are now teaching Vanilla Extract for those who want to learn high-performance styling techniques.
Comparing Emotion, Stitches, and Vanilla Extract
Let’s compare these three libraries side by side.
| Feature | Emotion | Stitches | Vanilla Extract |
| Type safety | Good | Excellent | Excellent |
| Runtime performance | Fast | Very fast | Zero runtime |
| Theming support | Yes | Yes | Yes |
| Learning curve | Easy | Easy to Medium | Medium |
| Styled components | Yes | Yes | No |
| Style separation | Inline | Inline | Separate files |
All three libraries are great choices, but the best one depends on your needs:
- Use Emotion for quick projects or if you want maximum flexibility.
- Use Stitches for type-safe styling with great theming support.
- Use Vanilla Extract when performance is your top priority.
Many projects built during a full stack course use a mix of these tools depending on the project goals and team experience.
The Future of CSS-in-JS
The future of CSS-in-JS is bright. As more developers use tools like TypeScript, the demand for type-safe styling libraries is growing. Libraries like Stitches and Vanilla Extract show that it’s possible to have both performance and safety.
Frameworks are also evolving. For example, newer versions of React and Next.js support better performance and developer tools. CSS-in-JS libraries will likely continue to improve to match these changes.
Students learning in full stack developer classes are encouraged to try different libraries and choose the one that works best for their projects. As they gain more experience, they learn how to make smart choices based on project size, team needs, and performance goals.
Conclusion
CSS-in-JS is an important part of modern web development. Libraries like Emotion, Stitches, and Vanilla Extract give developers powerful tools to write clean, reusable, and efficient styles. Each library has its strengths, and the best choice depends on your project and preferences.
If you are just beginning your web development journey, learning CSS-in-JS will give you a strong advantage. It helps you build better applications and prepares you for working on real-world projects. Whether you choose Emotion, Stitches, or Vanilla Extract, the key is to understand how styles and components work together.
Joining a full stack course is a great way to get hands-on experience with these tools. You’ll build real projects, understand best practices, and become a more confident developer.
The future of CSS-in-JS is exciting, and now is the perfect time to learn and grow with it.
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