N-gones - Slow version

speed=25; t.cs().hideTurtle().setProperty({strokeWidth:4,strokeOpacity:0.6,fillOpacity:0.3}); ngon(10,60);

<jsxgraph width="600" height="600">-->
var brd = JXG.JSXGraph.initBoard('jxgbox', {originX:300, originY:300, unitX:1, unitY:1});
var t = brd.createElement('turtle',[],{fillColor:'yellow'});
var speed;

function innerloop(i,j,ne,sz) {
   if (i>0) {
     if (j==ne) { t.rt(360/ne); }
     t.rt(360/ne);
     t.fd(sz);
     j--;
     if (j<=0) {
       j=ne;
       i--;
     }
     var st = 'innerloop('+(i)+','+(j)+','+(ne)+','+(sz)+')';
     setTimeout(st,speed);
   }
}

function ngon(ne,sz) {
  innerloop(ne,ne,ne,sz);
}

function runturtle() {
  var code = $('inputtext').value;
  if (code=='') { return; }
  eval(code);
}
function clearturtle() {
  t.cs();
}
</jsxgraph>