var Person = function(name,sex){     this.name = name;     this.sex = sex;          var _privateVariable = "";//私有变量         //构造器中定义的方法，即为私有方法     function privateMethod(){            _privateVariable = "private value";         alert("私有方法被调用！私有成员值：" + _privateVariable);                  }     privateMethod(); //构造器内部可以调用私有方法             } Person.prototype.sayHello = function(){     alert("姓名：" + this.name + "，性别：" + this.sex); } var p = new Person("菩提树下的杨过","男");       p.sayHello(); //p.privateMethod();//这里将报错，私成方法无法被实例调用 alert(p._privateVariable);//显示: undefined

var Person = function(){         var salary = 0.0;     this.setSalary = function(value){         salary = value;     }     this.getSalary = function(){         return salary;     } } var p = new Person(); p.setSalary(1000); alert(p.getSalary());//返回1000 alert(p.salary);//返回undefined