Extending Objects in Ext JS
And the output:
You’re welcome to click back or open a new tab to compare this to the previous post, but this is different from the jQuery example. The single difference is that the desc property doesn’t exist in our extended object. Ext JS has decided that a property with a null value will overwrite a previous value (see title), but an undefined value will in effect erase the property.
For more information: Function-method-apply