Layui is a classic web UI component library written in pure HTML, CSS, and JavaScript. It provides a comprehensive set of 20+ interactive components including tables, forms, modals, date pickers, menus, trees, and more. The library follows a modular architecture with ES modules, a core component base class, and a consistent lifecycle (render/reload/destroy). It includes built-in internationalization, a resource loader, a simple front-end router, and a template engine (laytpl, though deprecated). The codebase is actively developed (v3.0.0-alpha.3) with modern build tooling (Rollup, PostCSS, ESLint) but retains some legacy patterns and a dependency on jQuery. The component base class and popup system are well-architected and reusable, while some modules (table, treeTable) are large and monolithic. Testing is incomplete, with unit tests marked as placeholder and visual tests requiring manual execution.