Get the current Value from a TextField in extJS !

Get the Current(or the latest) Value from the textField:

var currentValue= Ext.getCmp('expName').value;

Get the value that was initially loaded (or initialized)
var loadedValue=Ext.getCmp('expName').getValue();


On a separate note, You can define a label with a html message into it.
For example :
  {xtype:'label', 
   id:'duplicate_warning_msg',
   html:''Duplicate value detected !', hidden:true 
   }

You can make it visible or hide it with setVisible method as following.
Ext.getCmp('duplicate_warning_msg').setVisible(true);