Below example shows how to draw circle:
<!DOCTYPE html> <html> <body> <canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;"> Your browser does not support the HTML5 canvas tag.</canvas> <script> var c = document.getElementById("myCanvas"); var ctx = c.getContext("2d"); ctx.beginPath(); ctx.arc(100, 75, 50, 0, 2 * Math.PI); ctx.stroke(); </script> </body> </html>