javascript tree generator

gistfile1.js

function randomRange(lowerBound, upperBound){
    return lowerBound + Math.random() * (upperBound-lowerBound);
}
function draw() {
    var canvas = document.getElementById("canvas");
    var c = canvas.getContext("2d");
    
    function drawBranch(l, direction) {
          c.save();
          c.fillRect(-1, 0, 2, -l);
          c.translate(0, -l);
          if ( l > 5 ) {
              drawBranch(l * randomRange(0.7, 0.9), -direction);
              c.rotate(randRange(0.5, 0.6) * -direction);
              drawBranch(l * randomRange(0.6, 0.8), direction);
              if (Math.random() > 0.2){
                drawBranch(l * randomRange(0.3, 0.5), -direction);
              }
          }else {
              var r = Math.random();
              if (r < 1.55){
                  c.fillStyle = "green";
              }else if (r < 1.75){
                  c.fillStyle = "orange";
              }else{
                  c.fillStyle = "red";
              }
              c.fillRect(-2, -2, 4, 4);
          }
          c.restore();
    }
    c.translate(200, 300);
    drawBranch(50, 1);
}