add.jQuery.js

(function AddjQuery() {    
    var el = document.createElement("script"),
    loaded = false;
    el.onload = el.onreadystatechange = function () {
      if ((el.readyState && el.readyState !== "complete" && el.readyState !== "loaded") || loaded) {
        return false;
      }
      el.onload = el.onreadystatechange = null;
      loaded = true;
      // done!
    };
    el.async = true;
    el.src = 'http://code.jquery.com/jquery-1.8.0.js';
    var bhead = document.getElementsByTagName('head')[0];
    bhead.insertBefore(el, bhead.firstChild);
}) ();