title: draw arc with requestAnimationFrame
body: <p><a href="http://jsfiddle.net/EKz29/4/" rel="nofollow"><strong><em>FIDDLE</em></strong></a></p>
  
  <p><strong>What I am doing</strong>:I am drawing a cirlce from an arc using set interval.After a circle is drawn,i  am drawing another circle with slightly increased radius as seen in fiddle.</p>
  
  <p><strong>What I want to do</strong>:I want to achieve same functionality,but a circle should be completed at 1min(i.e 60 sec to draw a circle.) using <em>requestAnimationFrame</em> and avoiding setInterval.</p>
  
  <p>I know what RAF is,but unable to implement it</p>
  
  <p><strong>60 sec...RAF...Circle.</strong>??
  My code:</p>
  
  <pre><code>    //for full code see the fiddle.
  
      setInterval(function () {
      context.save();
      //context.clearRect(0, 0, 500, 400);
      context.beginPath();
  
      increase_end_angle = increase_end_angle + 11 / 500;
      dynamic_end_angle = end_angle + increase_end_angle;
      context.arc(x, y, radius, start_angle, dynamic_end_angle, false);
  
      context.lineWidth = 6;
      context.lineCap = "round";
      context.stroke();
      context.restore();
      if (dynamic_end_angle &gt; 3.5 * Math.PI) { //condition for if circle completion
          increase_end_angle = 0;
          draw(radius + 10); //draw from same origin.
      }
  }, 3);
  </code></pre>
  
  <p><em><strong>Updated questions for Ken only</em></strong>:</p>
  
  <p>1)how does multiplying everything by 2(i.e scale) makes everything sharper.</p>
  
  <p>2)i dint understood the setInterval(anim, 120);//this part..ratio..is this why circle gets completed at 60 seconds? and again i am always doubtful when using setInterval.Reason being it does provides jerk after some time.Not in this case though.I dint wanted my animation to stop which always happened when using RAF.But again raf would be great for optimization.So a little confusion was there,but i guess i will go by the setInterval way.</p>
  
  <p>3)this question is a little difficult and i am working on it for now.In case I am not able to do it,i would take your advice.It deals with some json,creating multiple instances and stopping the animation when data stops coming.I will try that tomorrow,too tiredd now.</p>
  
  <p>Thanks for the answer ken!!!exactly what i wanted. </p>