``` 构造函数模式用于定义实例属性，而原型模式用于定义方法和共享的属性 每个实例都会有自己的一份实例属性的副本，但同时又共享着对方法的引用，最大限度地节省了内存。 ``` ``` function Person(name, age, job){ this.name = name; this.age = age; this.job = job; this.friends = ["Shelby", "Court"]; } Person.prototype = { constructor : Person, sayName : function(){ alert(this.name); } } var person1 = new Person("Nicholas", 29, "Software Engineer"); var person2 = new Person("Greg", 27, "Doctor"); person1.friends.push("Van"); alert(person1.friends); //"Shelby,Count,Van" alert(person2.friends); //"Shelby,Count" alert(person1.friends === person2.friends); //false alert(person1.sayName === person2.sayName); //true ```