JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" type="text/css" href="//cdn.sencha.io/ext-4.1.0-gpl/resources/css/ext-all-debug.css"
/>

JavaScript

Ext.define("User", {
    extend: 'Ext.data.Model',
    fields: [
         {name: 'id', type: 'int'},
         {name: 'name',  type: 'string'},
         {name: 'email', type: 'string'}
    ],
    /* Relation with Student Model */
    hasMany: {
        model: 'Book',
        name: 'books'
    }
});

Ext.define("Book", {
    extend: 'Ext.data.Model',
    fields: [
        {name: 'id', type: 'int'},
        {name: 'title', type: 'string'},            //,mapping:'record[0].title'    not working
        {name: 'userId', type: 'int'}
    ]
});


var data = {
    "success": "true",
    "users": [
        {
            "id": "1",
            "name": "shilpa",
            "email": "[email protected]",
            "books": [
                {
                    "id": "10",
                    "title": "c++",
                    "userId": "1"
                },
                {
                    "id": "11",
                    "title": "Java",
                    "userId": "1"
                }
            ]
        }
    ]
};

var store = Ext.create('Ext.data.Store', {
    model: "User",
    autoLoad: true,
    data: data,
    proxy: {
        type: 'memory',
        reader: {
            type: 'json',
            root: 'users',
            successProperty: 'success'
        }
    }
});



Ext.create('Ext.grid.Panel', {
    title: 'Users',
    store: store,
    columns: [{
        text: 'Name',
        dataIndex: 'name'
    }, {
        text: 'Email',
        dataIndex: 'email',
        flex: 1
    
    },{
        text: 'Books',
        renderer: function (val, meta, record) {
            var books = '';
            record.books().each(function(bookRecord, index, count) {
                books = books + bookRecord.get('title') + ',';
            });
            return books;
        }
    }
             
             ],
    height: 200,
    width: 500,
    renderTo: Ext.getBody()
});