Popper

The Polymer library provides a set of features for creating custom elements. These features are designed to make it easier and faster to make custom elements that work like standard DOM elements. Similar to standard DOM elements, Polymer elements can be instantiated using a constructor or document creation element, configured using attributes or properties, populated with internal DOM inside each instance, responsive to property and attribute changes, styled with internal defaults or externally, and responsive to methods that manipulate its internal state. Registering an element associates a class with a custom element name. The element provides callbacks to manage its lifecycle. Polymer also lets you declare properties, to integrate your element's property API with the Polymer data system. Shadow DOM provides a local, encapsulated DOM tree for your element. Polymer can automatically create and populate a shadow tree for your element from a DOM template.

A simple library to take care of complicated animations. You can also add custom functions that do non-CSS animations! Install and save to your package.json, and include it in your Javascript. Brew up some instant scroll animations. Animate based on scroll location, animate based on mouse X location and create multiple animations based on mouse X location. Now you can create an instance of Choreographer, and run the animations based on whatever measurement floats your boat (ex. scroll position, mouse position, timestamp, whatever). The easiest way to understand how this all works is to check out the examples. Bugs will occur if you overlap animation ranges that affect the same style properties! There are two built-in animation functions available, called 'scale' and 'change'. Progress is what allows for progressive scaling of values (ex. smooth fading of opacity, 2d translation, etc.) If the value is between 0 and 1, that means you are within a range.