MB zoom circles in and out

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.background {
  fill: none;
  pointer-events: all; 
}

.feature {
  fill: #ccc;
  cursor: pointer;
}

</style>
<body>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/topojson.v1.min.js"></script>
<script>

var    active = d3.select(null);
 
var jsonCircles = [
 { "x":50, "y": 50, "radius": 20, "color" : "green" },
 { "x": 100, "y": 50, "radius": 20, "color" : "purple"},
 { "x": 150, "y": 50, "radius": 20, "color" : "red"}];

var zoom = d3.zoom()
    .on("zoom", zoomed);
  
var initialTransform = d3.zoomIdentity
    .translate(0,0)
    .scale(1.0);

var svg = d3.select("body").append("svg")

//var width = svg.node().getBoundingClientRect().width
//var height = svg.node().getBoundingClientRect().height;

var width = window.innerWidth;
var height = window.innerHeight;
 
 svg.attr("width", width)
    .attr("height", height)
    .on("click", stopped, true);
 
 svg.append("rect")
    .attr("class", "background")
    .attr("width", width)
    .attr("height", height)
		.style("fill", "white")
		.style("stroke", "black")
    .on("click", reset);
  
var g = svg.append("g");

svg
    .call(zoom) // delete this line to disable free zooming
    .call(zoom.transform, initialTransform);

function clicked(d) {
  if (active.node() === this) return reset();
  active.classed("active", false);
  active = d3.select(this).classed("active", true);
      dx = d.radius
      dy = d.radius
      x =  d.x 
      y = d.y
      scale = Math.max(1, Math.min(8, 0.9 / Math.max(dx / width, dy / height))),
      translate = [width / 2 - scale * x, height / 2 - scale * y];
 
  console.log("width");
  
  var transform = d3.zoomIdentity
    .translate(translate[0], translate[1])
    .scale(scale);

svg.transition()
      .duration(750)
      .call(zoom.transform, transform);
}

function reset() {
  active.classed("active", false);
  active = d3.select(null);

svg.transition()
      .duration(750)
      .call(zoom.transform, initialTransform);
}

function zoomed() {
  var transform = d3.event.transform;

g.style("stroke-width", 1.5 / transform.k + "px");
  g.attr("transform", transform);
}

// If the drag behavior prevents the default click,
// also stop propagation so we don’t click-to-zoom.
function stopped() {
  if (d3.event.defaultPrevented) d3.event.stopPropagation();
}

</script>

https://d3js.org/d3.v4.min.js

https://d3js.org/topojson.v1.min.js