Read about the cartography driving this javascript map layer here.
Update! We have just presented the theory and methods that drive our Canvas Flowmap Javascript Layer at the 2017 North American Cartographic Information Society in Montréal this past month (October 2017). Here's a video of our presentation if you're interested.
This Canvas-Flowmap-Layer is an extension of the ArcGIS API for JavaScript (Esri JSAPI) for the purpose of mapping the flow of objects from an origin point to a destination point by using a Bezier curve. It was created in collaboration Esri colleague, Jacob Wasilkowski. Since creating this JavaScript layer, Jacob and I started a geo-viz collaboration website, that you can find here.