Ext类继承

var Person = Ext.emptyFn;
  Ext.apply(Person.prototype,{
   id:0,
   name:"",
   print:function(){
    alert(String.format("id={0},name={1}",this.id,this.name));
   }
  });
  
  /************************** 继承。******************/
  var Student = function(cfg) {
   Ext.apply(this,cfg);
  }
  
  // 类Student继承Person，并增加了一个字段address
  Ext.extend(Student,Person,{
   address:""
  });
  
  var student = new Student();
  student.id = 2000;
  student.name = "extends";
  student.address =  "深圳市";
  student.print();
  alert(student.address);
  
  student = new Student({id:3000,name:"china",address:"hub"});
  student.print();