I can solve this problem insert tha follow instruction : if (isNaN(g)) g = 0; afer if (l.prop == "height") { g = (l.now - l.start) / (l.end - l.start); }
so ... step: function(k, l) { if (l.prop == "height") { g = (l.now - l.start) / (l.end - l.start); } if (isNaN(g)) g = 0; j.toShow[0].style[l.prop] = (g * d [l.prop].value) + d[l.prop].unit; }, ...