Question

When does initialConfig get called? What’s the difference between it and initComponent?

Answer 1

initialConfig never gets called, because it is not a function.
It’s the configuration object, that was used to configure the component when it was actually created.

For example when you do:

var textField = new Ext.form.TextField({
  fieldLabel: 'A textfield',
  itemId: 'textField'
});

the

{
  fieldLabel: 'A textfield',
  itemId: 'textField'
}

object becomes a read only property textField.initialConfig

initComponent() is a private function, that is responsible for configuring the component during creation.