JS Data Vis SRC Demo SRC

<!DOCTYPE html>
<meta charset="utf-8">
<body bgcolor="grey">
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
var tau = 2 * Math.PI;
var arc = d3.arc()
    .innerRadius(180)
    .outerRadius(240)
    .startAngle(0);

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    g = svg.append("g").attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
var background = g.append("path")
    .datum({endAngle: tau})
    .style("fill", "#000")
    .attr("d", arc);
var foreground = g.append("path")
    .datum({endAngle: 0.127 * tau})
    .style("fill", "red")
    .attr("d", arc);
d3.interval(function() {
  foreground.transition()
      .duration(750)
      .attrTween("d", arcTween(Math.random() * tau));
}, 100);

function arcTween(newAngle) {

  return function(d) {

    var interpolate = d3.interpolate(d.endAngle, newAngle);

    return function(t) {

      d.endAngle = interpolate(t);

      return arc(d);
    };
  };
}
</script>