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.
Great indeed! Though I believe the code should be updated as to d3 version 5. I got here from the Leanpub link of the book.