This bl.ock demonstrates the range of interpolation curves available in v4 of d3.js.
You can click on any of the legend labels to toggle visibility of the lines.
Details of the curve can be found on the D3 wiki.
This graph is part of the code samples for the update to the book D3 Tips and Tricks to version 4 of d3.js.
forked from d3noob's block: v4 curve interpolation comparison
https://d3js.org/d3.v4.min.js