WinJS

WinJS is not that easy to classify. It's not a full-on JS framework, it's not a mobile development kit, it's not a CSS framework, it's not a UI toolkit either.

WinJS actually merges concepts from all, providing a wide set of tools that developers can use in creating applications that run the same on Windows desktop or mobile applications, specifically developed for the Modern UI (formerly known as Metro).

The project is open sourced (unlike many other Microsoft projects) and can be used for any type of applications, coming packed with lots of ready-made controls and tools.

Supported components:
Listview
FlipView
NavBar
AppBar
Tooltip
Pivot
Toggles
Search box
Date picker
Time picker
Rating system
Template engine
Animation engine
Zooming
Flyout
Repeater
AJAX
Binding
Scheduler
Promises

Requirements:

• JavaScript enabled on client side