Metal.js is not a library of components, but a foundation for creating the components you need.
Used in numerous production environments already, Metal.js is the backbone of many frontend projects.
Metal.js components can be written in two templating languages, Soy (Google Closure), and JSX (React). Both are compiled to incremental dom which is used to progressively update DOM elements when component state updates. Therefore, you can spend less time doing manual DOM manipulation, and more time on what matters.