Vue.js - Reactive Components for Modern Web Interfaces
Inferno - An extremely fast React-like javascript library for building modern user interfaces.
Polymer - Polymer is a library that uses the latest web technologies to let you create custom HTML elements.
Preact.js - Preact is a fast 3kB alternative to React with the same modern API. Components & Virtual DOM.
w2ui - W2UI is a small JavaScript UI library with a complete set of widgets: layout, grid, sidebar, toolbar, tabs, fields, popup, utilities.
Sencha Ext JS - Sencha Ext JS is the most comprehensive JavaScript framework for building data-intensive, cross-platform web and mobile applications for any modern device. Ext JS includes 140+ pre-integrated and tested high-performance UI components.