Stripped adaptation of Jfire.io animation, for teaching purposes: more difficult by zanarmstrong

index.html

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
  <style>

  </style>
</head>

<body>
  <script>

  // created by //jfire.io/animations/2015-03-09/, adapted for demo
var width = 500,
    height = 500,
    n = 20;
    
var margin = {top: 20, right: 10, bottom: 20, left: 10};
var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height)

var g = svg.selectAll(".groups")
    .data(d3.range(n))
    .enter().append("g").attr("class", "group");
// step #1 -> what elements/attributes do you need to define?
g.append("xxx")."xxxxxx"

g.selectAll("xxxxxx")
    .data(["xxxx", "xxxxx"])
    .enter().append("xxxxx")
// step #2: write a translation and scalar function to replace the xxxx's below 
g.attr("transform", function(d) {return "translate(xxxxxx)scale(xxxxx)";})

// step #3: add time as an element in your translation function to animate
/*
d3.timer(function(time) {
g.attr("transform", function(d) {return "translate(xxxxxx)scale(xxxxx)";})
    });
    */

  </script>
</body>