injecting script tag

http://stackoverflow.com/questions/9424549/can-i-use-exts-loader-to-load-non-ext-scripts-object-dynamically

HTML

<link rel="stylesheet" href="http://dev.sencha.com/deploy/ext-4.0.7-gpl/resources/css/ext-all.css">

JavaScript

var onError = function() {
    // run this code on error
};
var onLoad = function() {
    $('body').html('jquery <br/><b>is loaded successfully</b>');
};
Ext.Loader.injectScriptElement('http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.min.js', onLoad, onError);