title: Adding dynamic fields on click of button in extjs 4
body: <p>I want to add a field dynamically when click on button in extjs 4.What I have done is added a onchange function on add button and write the adding textfield logic in that function.
  Here is my code.</p>
  
  <pre><code>Ext.define('AM.view.user.Edit', {
      extend: 'Ext.window.Window',
      alias : 'widget.useredit',
      requires: ['Ext.form.Panel'],
      title : 'Edit User',
      layout: 'fit',
      autoShow: true,
      height: 300,
      width: 280,
      id : 'mainPanel',
          initComponent: function() {
          this.items = [
              {
                  xtype: 'form',
                  id: 'dyForm',
                  padding: '5 5 0 5',
                  border: false,
                  style: 'background-color: #fff;',
  
                  items: [
                      {
                          xtype: 'textfield',
                          name : 'name',
                          fieldLabel: 'Name'
                      },
                      {
                          xtype: 'textfield',
                          name : 'email',
                          fieldLabel: 'Email'
                      }
                  ]
              }
          ];
  
          this.buttons = [
              {
                  text: 'Save',
                  action: 'save'
              },
             {
                  text: 'Add',
                  scope: this,
                  handler: this.onChange
              },
             ];
  
          this.callParent(arguments);
      },
      onChange : function(){alert('test');
           var form=Ext.getCmp("mainPanel");
          form.items.add(Ext.create("Ext.form.field.Text", {fieldLabel:"First Name"}));
          form.doLayout(true);
     }
  });
  </code></pre>
  
  <p>And I also want that on edit of this form I will load data to those new fields that i have newly created dynamically.</p>