Programming turtle graphics

Input

• List of available commands

t.fd(100);

Source code

<link rel="stylesheet" type="text/css" href="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraph.css" />
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/prototype.js"></script>
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraphcore.js"></script>
<form><textarea id="inputtext" rows=3 cols=35 wrap="off" style="width:600px;">t.fd(100);</textarea><br />
<input type="button" value="run" onClick="run()">
<input type="button" value="clear" onClick="clearturtle()">
<input type="button" value="clear log" onClick="clearlog()">
</form>
<div id="box" class="jxgbox" style="width:600px; height:600px;"></div>
<pre id="logwindow" class="javascript javascript" style="font-family:monospace;"></pre>

var brd = JXG.JSXGraph.initBoard('box', {originX: 300, originY: 300, unitX: 1, unitY: 1});
var t = brd.createElement('turtle');
function run() {
  brd.suspendUpdate();
  var code = document.getElementById('inputtext').value;
  if (code=='') { return; }
  eval(code);
  document.getElementById('logwindow').innerHTML += code+'\n';
  //document.getElementById('inputtext').value = '';
  brd.unsuspendUpdate();
}
function clearturtle() {
  t.cs();
  //document.getElementById('inputtext').value = 't.fd(100);';
}
function clearlog() {
  document.getElementById('logwindow').innerHTML = '';
}
</script>

• Hints how to "Slow the turtle down"