title: How to set url and root dynamically in extjs
body: <p>Can anybody tell how to set the url and root of a store dynamically in Ext JS?</p>
  
  <p>I have created a store like the one below. I need to update the root and dynamically set the url inside a controller.</p>
  
  <pre><code>Ext.define('Test.store.TestStore', {
    extend: 'Ext.data.Store',
    model: 'Test.model.TestModel',
    storeId: 'testStore',
    proxy: {
      type: 'jsonp',
      reader: {
        type: 'json',
        root: 'responseXML'
      }
    }
  });
  </code></pre>
  
  <p>Thanks</p>