All the ExtJS documentation and examples I have read suggest calling superclass methods like this:

MyApp.MyPanel = Ext.extend(Ext.Panel, {
  initComponent: function() {
    // do something MyPanel specific here...
    MyApp.MyPanel.superclass.initComponent.call(this);
  }
});

I have been using this pattern for quite some time and the main problem is, that when you rename your class then you also have to change all the calls to superclass methods. That's quite inconvenient, often I will forget and then I have to track down strange errors.

But reading the source of Ext.extend() I discovered, that instead I could use the superclass() or super() methods that Ext.extend() adds to the prototype:

MyApp.MyPanel = Ext.extend(Ext.Panel, {
  initComponent: function() {
    // do something MyPanel specific here...
    this.superclass().initComponent.call(this);
  }
});

In this code renaming MyPanel to something else is simple - I just have to change the one line.

But I have doubts...

• I haven't seen this documented anywhere and the old wisdom says, I shouldn't rely on undocumented behaviour.

• I didn't found a single use of these superclass() and supr() methods in ExtJS source code. Why create them when you aren't going to use them?

• Maybe these methods were used in some older version of ExtJS but are deprecated now? But it seems such a useful feature, why would you deprecate it?

So, should I use these methods or not?