//定义一个有两个方法的类function Person(){}Person.prototype.married = function(){};Person.prototype.unmerried = function(){};//定义一个构造函数作为子类function Man(defaults){defaults = defaults || {};this.name = "Tom";this.age = defaults.age || 22;}//将Man类的原型设为Person类的实例，继承其内容Man.prototype = new Man();//将子类的constructor属性指向其自身的构造函数，默认指向的是父类的构造函数Man.prototype.constructor = Person;var tom = new Man();var jerry = new Man({age:20});alert(tom.age);alert(jerry.age);tom.married();jerry.unmerried();alert(tom.constructor == Man);alert(tom.constructor == Person);