Loading Circle V0 - Movement

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    const width = 960;
    const height = 500;
    
    const midWidth = Math.floor(width/2);
		const midHeight = Math.floor(height/2);
    
    const color = d3.scaleOrdinal(d3.schemeCategory10);
    
    let colorVar = 0;
    
    function rotateClockwise(transition) {
      transition
      	.duration(5000)
      	.ease(d3.easeLinear)
    		.attrTween("cx", function() {
        	let that = d3.select(this);
        	return function(t) {
            return(midWidth + 50 * Math.cos(2 * Math.PI * t));
          }
    		})
      	.attrTween("cy", function() {
        	let that = d3.select(this);
          return function(t) {
            return(midHeight + 50 * Math.sin(2 * Math.PI * t));
          }
      	}).on("end", function() {
        	d3.select(this).transition().call(rotateClockwise);
      	});;
    }
       
    const svg = d3.select("body").append("svg")
    	.attr("width", width)
      .attr("height", height);

const circle = svg.append("circle")
      .attr("cx", midWidth)
      .attr("cy", midHeight)
    	.attr("r", 20)
    	.attr("fill", color(colorVar++));
    
    circle.transition().call(rotateClockwise);
  </script>
</body>

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