Pulling data into d3.js : <p>I'm new to D3, and with a background in server-side development I find a few things confusing.  I still struggle to understand how to bring data in from outside sources.  In my case, I can see the benefit of pulling data from the database on demand and visualizing it, but how does that data get into D3?  I've attempted to pull it in through Ajax, but I haven't found a good D3 v4 demo that covers this.  Are there any?  Do most people write to csv/json/tsv files and import that way?  </p>
