Power series for the exponential function

// Board
board1 = JXG.JSXGraph.initBoard('jxgbox1', {originX: 300, originY: 250, unitX: 50, unitY: 10});
board1.suspendUpdate();
// Axes and Properties
board1.createElement('axis', [[0,0], [1,0]], {});
board1.createElement('axis', [[0,0], [0,1]], {});
//
board1.createElement('curve', 
        [function(t){ return t; }, function(t){ return Math.exp(t); }, "t", -10, 10],
        {strokeColor: "#cccccc"});
var s = board1.createElement('slider', [0.75,-2.0,5,0,12,0], {name:'S'});
var t = board1.createElement('text',[-4,8, function() {
		var val = 0;
		for(var i=0;i<= Math.floor(s.X()); i++) {
   			val+= 1.0/board1.factorial(i);
		}
		return 'e~'+board1.round(val,10);
	},
]);
board1.createElement('curve', [
	't', 
	function(t) {
		var val = 0;
		for(var i=0;i<= Math.floor(s.X()); i++) {
   			val+= Math.pow(t,i)/board1.factorial(i);
		}
		return val;
	},
"t", -10, 10], {strokeColor: "#bb0000", curveType:'plot'});
board1.unsuspendUpdate();