<link href="//cdn.bootcss.com/extjs/6.2.0/classic/theme-classic/resources/theme-classic-all.css" rel="stylesheet" />
<script type="text/javascript" src="//cdn.bootcss.com/extjs/6.2.0/ext-all.js"></script>
<script type="text/javascript">
Ext.create('Ext.Panel', {
renderTo: 'helloWorldPanel',
html: 'First Ext JS Hello World Program'
<div id="helloWorldPanel"></div>