Classnames

Classnames is a minimal JavaScript utility that helps you construct CSS class strings based on conditional logic. Instead of manually concatenating strings, developers can pass any combination of strings, arrays, or objects, and the library will output a clean, space-separated class list. When you provide an object, the keys represent class names and the boolean values determine whether each class should be included in the final string. This reduces boilerplate and the risk of typos or stray spaces, especially in React, Vue, or other component-based UIs where dynamic styling is common. The utility is small and framework-agnostic, so it can be used in Node, browser code, or any bundler setup including Browserify and Webpack. It maintains backwards compatibility while evolving (for example, introducing polyfill requirements for older browsers in newer versions), and it ships with TypeScript bindings for better type safety.