JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://cdn.sencha.com/ext/gpl/4.2.0/resources/css/ext-all.css">

JavaScript

var store = Ext.create('Ext.data.Store',{
    fields:['name','checked'],
    proxy:{
        type: 'memory',
        reader: {
            type: 'json',
            rootProperty: 'data'
        }
    }
});

var grid = Ext.create('Ext.grid.Panel',{
   selModel: Ext.create('Ext.selection.CheckboxModel',{
                type: 'checkboxmodel',
                mode: 'MULTI'
            }),
    columns: [{text:'Nombre',dataIndex:'name'}],
    store: store,
    renderTo: Ext.getBody()
});

store.on('refresh',function(){             
    var selectedRecords = []; 
    this.each(function(record){      
       if (record.get('checked') == true) {       
           selectedRecords.push(record);      
        }    
    });                    
        
 grid.getSelectionModel().select(selectedRecords);     

});

store.loadData([
    {name:'Juan',checked:false},
    {name:'Susan',checked:true},
    {name:'Crysfel',checked:true},
    {name:'Sara',checked:false},
    {name:'John Doe',checked:false},
    {name:'John Doe',checked:true}
]);