conditionally-load-jquery.js

// Conditionally Load jQuery (javascript)
// Source: https://gist.github.com/gists/902090/
var init, loadjQuery;

init = function() {
  jQuery(document).ready(function() {
    alert('Your Code Here');
  });
};

loadjQuery = function() {
  var jQ;
  if (!(typeof jQuery !== "undefined" && jQuery !== null)) {
    jQ = document.createElement('script');
    jQ.type = 'text/javascript';
    jQ.onload = jQ.onreadystatechange = init;
    //jQ.src = '//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js';
    jQ.src = '//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js';
    return document.body.appendChild(jQ);
  } else {
    return init();
  }
};

if (window.addEventListener) {
  window.addEventListener('load', loadjQuery, false);
} else if (window.attachEvent) {
  window.attachEvent('onload', loadjQuery);
}