The concept of generating CSS directly within JavaScript, known as CSS-in-JS, has gained considerable traction in recent years, especially with the rise of reactive frameworks like React and Svelte. While these frameworks don’t require CSS-in-JS for styling components, they often work seamlessly with it, leading to a proliferation of libraries specifically designed to support CSS generation in JavaScript.
In this overview, we’ll explore the essentials of CSS-in-JS and highlight several popular frameworks that help simplify its implementation.
What Is CSS-in-JS?
Traditionally, CSS styling approaches fall into two categories: inline styles defined directly in the HTML or separate CSS files loaded by the browser. CSS-in-JS introduces a third method, in which CSS is programmatically created in the JavaScript code itself. This approach allows styles to be generated on the fly, adjusting automatically based on application state, variables, or user interactions.
Benefits of CSS-in-JS
A significant advantage of CSS-in-JS is its integration with JavaScript’s full control over application data, making styles inherently reactive to changes in state or user interactions. Styles can dynamically adapt without relying on pre-defined CSS classes or external files. This capability simplifies complex scenarios like theming and component-specific styling within large applications, which would be more challenging to achieve with traditional CSS alone.
Considerations and Tradeoffs
However, CSS-in-JS comes with its own set of tradeoffs. The main downside is the added complexity it introduces, as CSS is now tied directly to JavaScript logic. This can lead to performance concerns if not carefully optimized, and developers must be mindful of the differences in managing styles through JavaScript versus traditional methods.