// Prevent variables from being global
(function () {

      /*
          1. Inject CSS which makes iframe invisible
      */

    var div = document.createElement('div'),
        ref = document.getElementsByTagName('base')[0] ||
              document.getElementsByTagName('script')[0];

    div.innerHTML = '&shy;<style> iframe { visibility: hidden; } </style>';

    ref.parentNode.insertBefore(div, ref);

    /*
        2. When window loads, remove that CSS,
           making iframe visible again
    */

    window.onload = function() {
        div.parentNode.removeChild(div);
    }

})();