My Favorite Tooltip: The Final Block
Understand the final block of code that projects a circle to the tooltip location.
Adding the circle to the graph
Adding the circle to the graph is actually fairly simple:
focus.append("circle")
.attr("class", "y")
.style("fill", "none")
.style("stroke", "blue")
.attr("r", 4);
If you’ve followed any of the other examples in “D3 Tips and Tricks,” ...