This is a simple line graph demonstrating the addition of scatterplot points to a line graph. This was written using d3.js v4 and is a follow on to the simple graph example here.
This graph is part of the code samples for the update to the book D3 Tips and Tricks to version 4 of d3.js.
Apologies Sir. I will correct in the v5 book. In the meantime, here is a link to the v5 Scatterplot version - https://gist.github.com/d3noob/a44d21b304b9f7260a284b1883232002. And here is a link to the v6 version - https://gist.github.com/d3noob/5680dd0089abdc5b15f188d5efe48852. There is also the v6 version of the book free to download from here if you want it. Thanks for the heads up.