JSFiddle - React, Tailwind, and code Playground

HTML

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

JavaScript

Ext.create('Ext.form.Panel', {
        title: 'Contact Info',
        width: 300,
        bodyPadding: 10,
        renderTo: Ext.getBody(),
        items: [{
            id: 'myButton',
            xtype: 'textfield',
            name: 'name',
            fieldLabel: 'Name',
            style: 'background-color: #ddd;',
            allowBlank: false,
            listeners: {
                render: function() {
                    this.getEl().on('mousedown', function(e, t, eOpts) {Ext.getCmp('myButton').setValue("TEXT")}); // Does not work!
                }
            }
        }]
    });