Web Animation challenge

Web Animation API challenge

// Write a wrapper around the Web Animations API

// takes a HTML element upon creation

// constructor exposes the HTML element, a `keyframe` array of keyframe objects and a `config` object

// the `keyframe` array has a minimum length of 2 (animation start and end), can't start an animation unless satisfied
// each object in the `keyframe` array has a CSS property and value with an optional `offset` property (between 0 - 1, for keyframe %)

// the config object specifies duration, easing and iterations

// exposes an `addKeyFrame` and `removeKeyFrame` method to modify the `keyframe` array
// exposes a `setAnimationProperties` method that allows you to set values only on duration, easing and iterations keys on config object
// exposes an `animate` method that starts the animation

// when called, the `animate` method returns an object that has 
// play, pause and cancel methods to control the element's animation

// the wrapper should first test that animations are available in the browser
// then test if the Web Animations API is available
// if animations are available but the Web Animations API is not, a fallback must be provided
// consider using the CSSOM to provide the fallback