Fractal Tree in JavaScript

Slide

<canvas id="my_canvas" width="1000" height="800"></canvas>
  <script>
  var myCanvas = document.getElementById("my_canvas");
  var ctx = myCanvas.getContext("2d");
  function draw(startX, startY, len, angle) {
      ctx.beginPath();
      ctx.save();

      ctx.translate(startX, startY);
      ctx.rotate(angle * Math.PI/180);
      ctx.moveTo(0, 0);
      ctx.lineTo(0, -len);
      ctx.stroke();

      if(len < 10) {
          ctx.restore();
          return;
      }

      draw(0, -len, len*0.8, -15);
      draw(0, -len, len*0.8, +15);

      ctx.restore();
  }
  draw(400, 600, 120, 0)       
  </script>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
</head>
<body>
    <canvas id="my_canvas" width="1000" height="800"></canvas>
    <script>
    var myCanvas = document.getElementById("my_canvas");
    var ctx = myCanvas.getContext("2d");
    function draw(startX, startY, len, angle, branchWidth) {
        ctx.lineWidth = branchWidth;

        ctx.beginPath();
        ctx.save();

        ctx.strokeStyle = "green";
        ctx.fillStyle = "green";

        ctx.translate(startX, startY);
        ctx.rotate(angle * Math.PI/180);
        ctx.moveTo(0, 0);
        ctx.lineTo(0, -len);
        ctx.stroke();

        ctx.shadowBlur = 15;
        ctx.shadowColor = "rgba(0,0,0,0.8)";

        if(len < 10) {
            ctx.restore();
            return;
        }

        draw(0, -len, len*0.8, angle-15, branchWidth*0.8);
        draw(0, -len, len*0.8, angle+15, branchWidth*0.8);

        ctx.restore();
    }
    draw(400, 600, 120, 0, 10)       
    </script>
</body>
</html>

Source: https://lautarolobo.xyz/blog/use-javascript-and-html5-to-code-a-fractal-tree/#h2-2