function TamVentana() {
  var Tamanyo = [0, 0];
  if (typeof window.innerWidth != 'undefined')
  {
    Tamanyo = [
        window.innerWidth,
        window.innerHeight
    ];
  }
  else if (typeof document.documentElement != 'undefined'
      && typeof document.documentElement.clientWidth !=
      'undefined' && document.documentElement.clientWidth != 0)
  {
 Tamanyo = [
        document.documentElement.clientWidth,
        document.documentElement.clientHeight
    ];
  }
  else   {
    Tamanyo = [
        document.getElementsByTagName('body')[0].clientWidth,
        document.getElementsByTagName('body')[0].clientHeight
    ];
  }
  return Tamanyo; 
}

/*
window.onresize = function() {
  var Tam = TamVentana();
  //alert('La ventana mide: [' + Tam[0] + ', ' + Tam[1] + ']');
};
*/