A little snippet to make sure that jQuery is loaded before running code.

includeJquery.js

(function($, callback) {
    if($) {
        callback();
        return;
    }
    var script = document.createElement('script');
    script.src = '//code.jquery.com/jquery-1.11.1.min.js';
    script.onload = callback;
    document.getElementsByTagName('body')[0].appendChild(script);
})(window['jQuery'], function() {
    var $ = jQuery;

    /** jQuery dependent code here. **/
    
    
    
});