HTML5 Game - Canvas Animation Angular velocity

Description

Angular velocity
Demo

<!doctype html>  
   <html>  
   <head>  
    <meta charset="utf-8">  
    <title>Velocity Angle</title>  
    <style>canvas{border:1px solid red;}</style>  
   </head>  
   <body>  
    <canvas id="canvas" width="400" height="400"></canvas>  
    <script>  
class Ball{    /*from w  w w  .  jav a  2  s  .  c o m*/
   constructor(radius, color) {  
     if (radius === undefined) { radius = 40; }  
     if (color === undefined) { color = "#ff0000"; }  
     this.x = 0;  
     this.y = 0;  
     this.radius = radius;  
     this.rotation = 0;  
     this.scaleX = 1;  
     this.scaleY = 1;  
     this.color = color;  
     this.lineWidth = 1;  
   }  
     
   draw(context) {  
     context.save();  
     context.translate(this.x, this.y);  
     context.rotate(this.rotation);  
     context.scale(this.scaleX, this.scaleY);  
     context.lineWidth = this.lineWidth;  
     context.fillStyle = this.color;  
     context.beginPath();  
     //x, y, radius, start_angle, end_angle, anti-clockwise  
     context.arc(0, 0, this.radius, 0, (Math.PI * 2), true);  
     context.closePath();  
     context.fill();  
     if (this.lineWidth > 0) {  
       context.stroke();  
     }  
     context.restore();  
   }
}
    window.onload = function () {  
      let canvas = document.getElementById('canvas'),  
          context = canvas.getContext('2d'),  
          ball = new Ball(),  
          angle = 45,  
          speed = 1;  

      ball.x = 50;  
      ball.y = 100;  

      (function drawFrame () {  
        window.requestAnimationFrame(drawFrame, canvas);  
        context.clearRect(0, 0, canvas.width, canvas.height);  

        let radians = angle * Math.PI / 180,  
            vx = Math.cos(radians) * speed,  
            vy = Math.sin(radians) * speed;  

        ball.x += vx;  
        ball.y += vy;  
        ball.draw(context);  
      }());  
    };  
    </script>  
   </body>  
   </html>