Inspired by Trulia Trends - but with code and using SVG.
Example data shows concurrent user sessions over time, taken from a development environment.
MIT Licensed, see LICENSE.MD.
forked from tjdecke's block: HW2&3_Heatmap
Modified http://d3js.org/d3.v3.js to a secure url
https://d3js.org/d3.v3.js