<script src="http://spelprogrammering.nu/simple.js">
function start()
{
  var l_system = 'F';

  var rules  = {'F': 'F+F--F+F', 
                '+': '+', 
                '-': '-'};
  
  var events  = {};
  events['F'] = function() { turtle.move(length); };
  events['+'] = function() { turtle.turnLeft(angle); };
  events['-'] = function() { turtle.turnRight(angle); };

  var iterations = 3;
  var angle      = 60;
  var length     = 10;
    
  for (var i = 0; i < iterations; i++)
  {
    var currentLength = l_system.length;
    var newSystem = '';
    for (var u = 0; u < currentLength; u++) 
    { 
      newSystem += rules[l_system[u]]; 
    }
    l_system = newSystem;
  }
  
  for (var i = 0; i < l_system.length; i++)
  {
    events[l_system[i]]();
  }
}
</script>