A streamgraph is a type of stacked area chart. It represents the evolution of a numerical variable for several groups. Areas are usually displayed around a central axis, and edges are rounded to give a flowing shape.
          Building a streamgraph follows the same process than for a
          stacked area chart. Stack the data with
          the d3.stack() function, but use the
          stackOffsetSilhouette offset to position shapes around
          the central axis.
        
          Here is a streamchart showing the evolution of a few baby names in the
          US during the previous century.
          Read more
          about it here. Axis are customized, color palette is used, hover
          feature is added.
Hover a group to get the name.
        
A few blocks with more complicated codes to showcase the possibility of d3 for streamgraphs.