CSS, Web Design

The Battle Between CSS-in-JS and Traditional CSS: Pros, Cons, and Best Practices

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If you’re a web developer, chances are you’ve heard of both CSS-in-JS and traditional CSS. Let’s start with a quick explanation of each:

  • CSS-in-JS: A method of styling web pages where CSS styles are written in JavaScript files and applied to components at runtime.
  • Traditional CSS: The standard way of styling web pages using a separate CSS file or inline styles within HTML markup.

CSS-in-JS is a relatively new approach that has gained popularity in recent years. However, traditional CSS has been around since the early days of the web. It’s important to compare these two approaches to understand their pros, cons, and best practices.

Pros and Cons of CSS-in-JS


CSS-in-JS is gaining popularity as it offers some unique benefits over traditional CSS. Here are some of the pros of using CSS-in-JS:

  • Scoped styles: With CSS-in-JS, styles are scoped to specific components or elements, making it easier to manage and avoid style conflicts.
  • Dynamic styles: CSS-in-JS allows you to easily create dynamic styles based on the state of the component or user interactions. This can be challenging with traditional CSS.
  • Elimination of class naming conflicts: Since CSS-in-JS generates unique class names for each component, there is no risk of class naming conflicts that often occur in traditional CSS.
  • Better performance with fewer requests: With CSS-in-JS, all the styles required for a component are included in the JavaScript bundle, reducing the number of HTTP requests needed to render a page.
  • Easy to maintain and reuse code: CSS-in-JS keeps your styles close to your components, making it easier to maintain and reuse code in different parts of your application.


While CSS-in-JS has many benefits, it also has some drawbacks that should be considered:

  • Steep learning curve: Learning how to use CSS-in-JS can be challenging, especially if you’re used to traditional CSS. It requires a different way of thinking about styling and may take time to get used to.
  • Adds complexity to the application: CSS-in-JS adds another layer of complexity to your application, which can make it harder to debug and maintain.
  • Limited tooling support: While there are many libraries available for CSS-in-JS, not all of them have the same level of tooling support as traditional CSS tools like Sass or Less.
  • Runtime overhead: Since styles are generated at runtime, there may be some performance overhead when using CSS-in-JS. However, this can often be mitigated by using server-side rendering or code splitting.
  • Can be less readable than traditional CSS: Some people find that the inline styles used in CSS-in-JS can be less readable than traditional CSS. This can be mitigated by using a library that allows you to write your styles in a more CSS-like syntax.

Pros and Cons of Traditional CSS


  • Simple syntax
  • Widespread adoption and tooling support
  • Large community resources and documentation
  • Separation of concerns
  • Faster load times

CSS has been around for a long time, and its syntax is simple and easy to learn. Since it has been widely adopted, there are plenty of tools and resources available for developers to use. This includes editors with syntax highlighting and autocompletion, and libraries that provide pre-built UI components.

One of the key benefits of CSS is the separation of concerns it allows. By separating style from content and behavior, you can keep your code organized and easier to maintain. Additionally, since CSS is loaded separately from HTML, it helps to make web pages load faster.


  • Global scope can cause conflicts
  • Maintenance challenges
  • Lack of dynamic capabilities
  • Not as reusable as CSS-in-JS

One of the biggest drawbacks of traditional CSS is its global scope. Since every rule you write applies to every matching element on the page, it’s easy to accidentally create conflicting styles. This can lead to unexpected behavior and make it difficult to maintain your code.

As CSS files grow in size, they can become difficult to manage and maintain. Refactoring becomes more challenging, and it can be hard to know if a change will impact other parts of the codebase. Additionally, CSS doesn’t have the same dynamic capabilities as JavaScript, which can make it challenging to create complex interactions and animations.

Finally, while CSS is reusable to some extent through classes and selectors, it’s not as flexible as CSS-in-JS. With CSS-in-JS, you can define styles directly in your component code, which makes it easier to create truly reusable UI components.

Best Practices for CSS-in-JS and Traditional CSS


CSS-in-JS is a powerful tool that allows you to write and use JavaScript code to generate CSS styles dynamically. Here are some best practices to follow when using CSS-in-JS:

  • Choose an appropriate library: There are many CSS-in-JS libraries available, each with its own strengths and weaknesses. Choose one that fits your needs and matches your skill level.
  • Use a consistent formatting style: Consistency is key to maintainability. Choose a consistent formatting style and stick to it throughout your project.
  • Utilize theme objects for easy customization: Theme objects allow you to store and reuse commonly used styles across your application. Use them to make customization easier and more efficient.
  • Limit the use of inline styles: While inline styles can be convenient, overuse can lead to messy and hard-to-maintain code. Use them sparingly.
  • Avoid excessive nesting: Excessive nesting can lead to overly complex and inefficient code. Keep your code as flat as possible.

Traditional CSS:

Traditional CSS is a tried-and-true approach to styling web pages. Here are some best practices to follow when using traditional CSS:

  • Use descriptive class names: Descriptive class names make your code more readable and maintainable. Avoid generic names like “container” or “wrapper.”
  • Follow the cascade hierarchy: The cascade hierarchy determines how styles are applied to elements. Knowing and following this hierarchy can help you write more efficient and effective CSS.
  • Use preprocessors like Sass or Less: Preprocessors can make your CSS more powerful by allowing you to use variables, mixins, and other features that are not available in standard CSS.
  • Optimize CSS for performance: Large CSS files can slow down page load times. Optimize your CSS by removing unused styles and minimizing file size.
  • Use a CSS reset: Different browsers have different default styles for HTML elements. Using a CSS reset can help ensure consistent styling across browsers.


In this article, we have explored the pros and cons of using CSS-in-JS and traditional CSS approaches to styling web applications. We have discussed how CSS-in-JS offers benefits such as scoped styles, dynamic styles, and improved code maintainability, while traditional CSS provides a more familiar syntax, better browser compatibility, and easier integration with existing tools.

It is essential to note that both approaches have their strengths and weaknesses and can be suitable for different projects depending on the requirements and preferences of the developers involved.

Choosing between CSS-in-JS and traditional CSS can be a challenging decision, and ultimately it depends on the specific needs and goals of the project. Suppose you are working on a complex application that requires a high degree of dynamism and scalability. In that case, CSS-in-JS might be a better choice because of its flexibility and ability to manage stateful styles easily. However, if you are working on a project that requires a simple layout and does not need any dynamic behavior, traditional CSS might be a better option because of its familiarity and ease of use.

Overall, it is essential to weigh the pros and cons of both approaches before deciding which one to use. It is also possible to combine both approaches in a single project, using traditional CSS for static styles and CSS-in-JS for dynamic elements or components.

Future developments in the field

The battle between CSS-in-JS and traditional CSS is far from over, and there are exciting developments happening in the field.

One significant development is the emergence of design systems, which provide a comprehensive set of pre-built UI components that can be easily customized and integrated into any project. Design systems help promote consistency and improve code maintainability, regardless of the styling approach used.

Another development is the increasing popularity of CSS modules, which offer a way to write modular, reusable CSS code that can be easily scoped and imported into different parts of an application. CSS modules provide a similar level of modularity and encapsulation as CSS-in-JS while using traditional CSS syntax.

In conclusion, the field of web styling continues to evolve, and developers must stay up-to-date with the latest trends and best practices to make informed decisions about which approach to use.

About the author / 

Mohamed Rias

I'm a programmer, photographer, and proud parent. With a passion for coding and a love of capturing life's moments through my camera lens, I'm always on the lookout for new challenges and opportunities to grow. As a dedicated parent, I understand the importance of balancing work and family, and I strive to be the best version of myself in all aspects of my life.

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