reactjss

ReactJSS is an open‑source library that integrates JSS, a CSS-in-JS styling solution, with React applications. It provides a JavaScript‑based approach to styling, generating unique class names and injecting styles into the document. By using ReactJSS, developers can define styles as JavaScript objects and apply them directly to components, enabling dynamic and themeable UI without separate CSS files.

Key features include theming support through a ThemeProvider, which allows styles to adapt to a given theme, and dynamic styling driven by component props. The library leverages the JSS plugin system for features such as nesting, composition, and vendor prefixing. ReactJSS exposes both a hook‑based API and, in older versions, a higher‑order component pattern (for example withStyles or injectSheet), providing flexibility for different codebases.

Usage involves defining a styles object, creating a useStyles hook or withStyles wrapper, obtaining a classes object, and applying class names to elements. A ThemeProvider supplies a theme object to styles. The approach supports server‑side rendering and is designed to integrate with existing React component trees, allowing dynamic theming and reusability across components without writing separate CSS files.

ReactJSS is part of the JSS ecosystem and is released under an open‑source license. It competes with other CSS‑in‑JS solutions and is commonly used in projects seeking co‑located styles, strong theme support, and programmatic style control in React.