JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://docs.sencha.com/ext-js/4-1/extjs-build/ext-all.js"></script>
<link rel="stylesheet" href="http://docs.sencha.com/ext-js/4-1/extjs-build/resources/css/ext-all.css">
<div id="cb1"></div>
<div id="cb2"></div>

JavaScript

Ext.onReady(function() {
    var names = Ext.create('Ext.data.Store', {
        fields: ['id', 'name', 'store'],
        data : [
            {"id":1, "name":"Tom", "store":"tomspets"},
            {"id":2, "name":"Lisa", "store":"lisaspets"},
            {"id":3, "name":"Anna", "store":"annaspets"}
            //...
        ]
    });
    
    Ext.create('Ext.data.Store', {
        fields: ['id', 'petname'],
        storeId: 'tomspets',
        data : [
            {"id":1, "petname":"White Cat"},
            {"id":2, "petname":"Orange Cat"}
        ]
    });
    
    Ext.create('Ext.data.Store', {
        fields: ['id', 'petname'],
        storeId: 'lisaspets',
        data : [
            {"id":1, "petname":"Dog"},
            {"id":2, "petname":"Cat"}
        ]
    });
    
    Ext.create('Ext.data.Store', {
        fields: ['id', 'petname'],
        storeId: 'annaspets',
        data : [
            {"id":1, "petname":"White Rabbit"},
            {"id":3, "petname":"Bronn Rabbit"}
            //...
        ]
    });
    
    var comp = Ext.create('Ext.form.field.ComboBox', {
        fieldLabel: 'Choose Pet',
        queryMode: 'local',
        renderTo: 'cb2'
    });
    
    var comp1 = Ext.create('Ext.form.field.ComboBox', {
        fieldLabel: 'Choose Name',
        store: names,
        queryMode: 'local',
        displayField: 'name',
        valueField: 'id', 
        renderTo: 'cb1',
        listeners: {
            select: function(checkbox,records) {
                comp.clearValue();
                console.log(records[0]);
                console.log(Ext.StoreMgr.lookup(records[0].data.store));
                comp.bindStore(Ext.StoreMgr.lookup(records[0].data.store));
                // you can change the value field if needed
                comp.displayField = 'petname'; 
                // you can change the display field if needed
                comp.valueField = 'id'; 
                // you can change the display template if needed
        ...