javascript中定义私有方法说明(private method)

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