Set values in ExtJS Grid

How to set values of components in an ExtJS Grid

HTML

<link rel="stylesheet" href="http://extjs.cachefly.net/ext-4.0.2a/resources/css/ext-all.css">
Check this for more details:<br/>
<a href='http://atechiediary.blogspot.com/2013/06/extjs-grid-update-values-of-elements-in.html'> Detail Blog entry </a>
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JavaScript

Ext.create('Ext.data.Store', {
    storeId: 'gridStore',
    fields: ['name', 'type', 'control'],
    data: {
        'items': [{
            'name': 'Name'
        }, {
            'name': 'Age'
        }, {
            'name': 'Sex'
        }]
    },
    proxy: {
        type: 'memory',
        reader: {
            type: 'json',
            root: 'items'
        }
    }
});

Ext.create('Ext.grid.Panel', {
    title: 'Set values in Grid',
    store: Ext.data.StoreManager.lookup('gridStore'),
    plugins: [
    Ext.create('Ext.grid.plugin.CellEditing', {
        clicksToEdit: 1
    })],
    columns: [{
        header: 'Field',
        dataIndex: 'name'
    }, { // Data Types
        xtype: 'gridcolumn',
        header: 'Type',
        dataIndex: 'type',
        field: {
            xtype: 'combo',
            store: new Ext.data.ArrayStore({
                fields: ['key', 'value'],
                data: [
                    ['Int', 'Int'],
                    ['Double',
                        'Double'],
                    ['Varchar', 'Varchar']
                ]
            }),
            displayField: 'value',
            valueField: 'key',
            emptyText: 'Select type...',
            listeners: {
                change: function (field, newValue, oldValue) {
                    // if type selected is varchar   
                    if (newValue == 'Varchar') {
                        // get the handler to the grid 
                        var grid = this.up().up();
                        // get selection model of the grid  
                        var selModel = grid.getSelectionModel();
                        // set control of the record to text  
                        //NOTE: 'control' here is the value set in the dataIndex property of the Control combobox  
                        selModel.getSelection()[0].set('control', 'TextField');
                    }
                }
            }
        }

    }, { // Control Types
        xtype:...