3 círculos usando canvas html5

<!DOCTYPE HTML>
<html>
  <head>
  <script src="https://d3js.org/d3.v3.min.js"></script>
    <style>
      body {
        margin: 0px;
        padding: 0px;
      }
    </style>
  </head>
  <body>
    <button type="button" id="clear">CLS</button>
    
    <canvas id="myCanvas" width="400" height="400"></canvas>
    <script>
      var canvas = document.getElementById('myCanvas');
      var context = canvas.getContext('2d');
      var centerX = canvas.width / 2;
      var centerY = canvas.height / 2;
      var radius = 60;

context.beginPath();
      context.arc(1/2 * centerX, centerY, radius, 0, 2 * Math.PI, false);
      context.fillStyle = 'red';
      context.fill();
      context.lineWidth = 2;
      context.strokeStyle = '#fff';
      context.stroke();

context.beginPath();
      context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);
      context.fillStyle = 'green';
      context.fill();
      context.lineWidth = 2;
      context.strokeStyle = '#fff';
      context.stroke();

context.beginPath();
      context.arc(3/2 * centerX, centerY, radius, 0, 2 * Math.PI, false);
      context.fillStyle = 'blue';
      context.fill();
      context.lineWidth = 2;
      context.strokeStyle = '#fff';
      context.stroke();
      
      d3.select('#clear').on('click', function() {
        context.clearRect(0, 0, canvas.width, canvas.height);
      }, false);
      
    </script>
  </body>
</html>

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

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