ExtJs继承
Javascript原始的继承写法：
Javascript代码 复制代码

// initComponent replaces the constructor:  Ext.Foo = Ext.extend(Ext.Bar, {    initComponent : function(){    // call superclass initComponent     Ext.Container.superclass.initComponent.call(this);   this.addEvents({   // add events     });     }   }  

1. Ext.extend adds the superclass property to the prototype of subclass (=the prototype of class you are extending from).
2. Ext.extend also adds a constructor property to the prototype of the subclass (=the class itself). It also adds a contructor to the prototype of the superclass if it is an Object.
3. With method.call(obj) you can execute a method in a specified scope (this=obj).