jQuery.noConflict() | Avoiding Conflicts with Other Libraries

(function() {
    function loadJQuery() {
      var startingTime = new Date().getTime();
      var script = document.createElement("SCRIPT");
      script.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js';
      script.type = 'text/javascript';
      script.onload = function() {
        var $j = jQuery.noConflict();
        jQuery = $;
        $(function() {
              var endingTime = new Date().getTime();
              var tookTime = endingTime - startingTime;
              window.alert("jQuery previous version=" + $.fn.jquery + ", version=" + $j.fn.jquery);
          });
      };
      document.getElementsByTagName("head")[0].appendChild(script);    
    }
    loadJQuery();
})();

Check here for JSFiddle