An example of d3-contour.
forked from mbostock's block: Contour Plot III
forked from enjalot's block: Contour Plot III
https://d3js.org/d3-array.v1.min.js
https://d3js.org/d3-color.v1.min.js
https://d3js.org/d3-contour.v1.min.js
https://d3js.org/d3-geo.v1.min.js
https://d3js.org/d3-interpolate.v1.min.js
https://d3js.org/d3-scale.v1.min.js
https://d3js.org/d3-scale-chromatic.v1.min.js
https://d3js.org/d3-timer.v1.min.js