Even simpler function plotter

The underlying JavaScript code

<input type="text" id="input" value="sin(x)*x">
<input type="button" value="plot" onClick="plotter()">
<input type="button" value="clear all" onClick="clearAll()">

var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-5,8,8,-5], axis:true});

function plotter() {
  var t = JXG.GeonextParser.geonext2JS(document.getElementById('input').value);
  var f = new Function('x','var y = '+t+'; return y;');
  board.create('functiongraph',[f,
                function(){ 
                  var c = new JXG.Coords(JXG.COORDS_BY_SCREEN,[0,0],board);
                  return c.usrCoords[1];
                },
                function(){ 
                  var c = new JXG.Coords(JXG.COORDS_BY_SCREEN,[board.canvasWidth,0],board);
                  return c.usrCoords[1];
                }
              ]);
}
function clearAll() {
    JXG.JSXGraph.freeBoard(board);
    board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-5,8,8,-5], axis:true});
}