JSFiddle - React, Tailwind, and code Playground

HTML

<p>In this example, two alert boxes will be popping up: one is before the store load, another one is after the store has finished loading</p>
<p>This is an example regarding coding style in ExtJS</p>

CSS

p{
    font-family:arial;
    font-size:12px;
    line-height:1.5;
    margin-bottom:10px;
}

JavaScript

Ext.define('MyApp.data.SimpleStore', {
    
    extend: 'Ext.data.Store',
    
    url: 'afsud',
    root: 'data',
    type: 'json',
    autoLoad: true,
    
    constructor: function(cfg) {
        var me = this;
       console.log("thisthisthisthisthisthisthis");
       
        Ext.apply(me, cfg || {});

        me.proxy = {
            type: 'ajax',
            url: me.url,
            reader: {
                type: me.type,
                root: me.root
            }
        };
        
        me.callParent(arguments);
        me.on('load', me.onStoreLoad, me);
        me.on('beforeload', me.onBeforeLoad, me);
    },

    onBeforeLoad: function(st) {
        alert('Store is trying to retrieve data from '+st.url);
    },
    
    onStoreLoad: function(st, records) {
        if (!records) alert('And it seems like we cannot reach '+st.url);
    }
});

var s = Ext.create('MyApp.data.SimpleStore', {
    url: 'test.php'
});