Position

windows is a handy, loosely-coupled jQuery plugin for full-screen scrolling windows.  This plugin simply opens up a handy API for position management, provides callbacks, and will allow for window snapping. No CSS is applied to the callee.  

Tether is a JavaScript library for efficiently making an absolutely positioned element stay next to another element on the page. For example, you might want a tooltip or dialog to open, and remain, next to the relevant item on the page.   This positioning plugin includes the ability to constrain the element within the viewport, its scroll parent, any other element on the page, or a fixed bounding box. When it exceeds those constraints it can be pinned to the edge, flip to the other side of its

Midway.js makes it super easy to automatically center the responsive elements on your websites. You all know and love the absolute positioning centering technique, but what happens when those centered elements change sizes, due to percentage based layouts? That's where Midway.js comes in.