d3.js Loading Spinner Icon

<!DOCTYPE HTML>
<html lang="en">
<head>
</head>
<body>

function loader(config) {
  return function() {
    var radius = Math.min(config.width, config.height) / 2;
    var tau = 2 * Math.PI;

var arc = d3.svg.arc()
            .innerRadius(radius*0.5)
            .outerRadius(radius*0.9)
            .startAngle(0);

var svg = d3.select(config.container).append("svg")
        .attr("id", config.id)
        .attr("width", config.width)
        .attr("height", config.height)
      .append("g")
        .attr("transform", "translate(" + config.width / 2 + "," + config.height / 2 + ")")

var background = svg.append("path")
            .datum({endAngle: 0.33*tau})
            .style("fill", "#4D4D4D")
            .attr("d", arc)
            .call(spin, 1500)

function spin(selection, duration) {
        selection.transition()
            .ease("linear")
            .duration(duration)
            .attrTween("transform", function() {
                return d3.interpolateString("rotate(0)", "rotate(360)");
            });

setTimeout(function() { spin(selection, duration); }, duration);
    }

function transitionFunction(path) {
        path.transition()
            .duration(7500)
            .attrTween("stroke-dasharray", tweenDash)
            .each("end", function() { d3.select(this).call(transition); });
    }

};
}

var myLoader = loader({width: 960, height: 500, container: "#loader_container", id: "loader"});
myLoader();

</script>

</body>
</html>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js