I've been playing with d3 recently, and it awesome! I'm especially amazed by the ease of animating transitions with it.

There are plenty of amazing d3 demos out there, but I wanted to write some simpler ones to help me understand the basics of d3. You can find them here:

http://calebmadrigal.github.io/d3-demos/

For example, here's how to draw a circle with d3:

Code:

  var width = 200;
  var height = 200;

  var x = width/2;
  var y = height/2;
  var ...