Function graph animation

The JavaScript code

  // User supplied function to be drawn.
  var f = function(x) { return Math.sin(x); };

  var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-5,2,5,-2], axis:true, keepaspectratio:false});

  var start = -4,
      end = 4,
      x = start,
      step = 0.2,
      turtle = brd.create('turtle', [x, f(x)]);

  var moveForward = function() {
         x += step;
         if (x>end) {
            return;
         }
         turtle.moveTo([x, f(x)]);
         setTimeout(moveForward, 200); // delay by 200 ms
     };

  turtle.hideTurtle();    // Hide the turtle arrow
  moveForward();          // Start the drawing