函数 var Prisoner = function(name,id) { this.name = name; this.id = id; }; //3.将构造函数关联到原型 Prisoner.prototype = proto; //4.实例化对象——采用工厂函数实例化对象 var makePrisoner = function(name,id) { //采用工厂函数实力化对象prisoner var prisoner = Object.create( proto ); prisoner.name = name; prisoner.id = id; return prisoner; };

var firstPrisoner = makePrisoner( 'Joe','12A' );

//firstPrisoner.sentence在firstPrisoner对象找不到sentence属性，
//所以查找对象的原型并找到了Both of these output 4
console.log( firstPrisoner.sentence );
console.log( firstPrisoner.proto.sentence );
//把对象的sentence属性设置为10
firstPrisoner.sentence = 10;
//outputs 10
//确定对象上的属性值已设置为10
console.log( firstPrisoner.sentence );
//但是对象的原型并没有变化，值仍然为4
console.log( firstPrisoner.proto.sentence );
//为了使获取到的属性回到原型的值，将属性从对象上删除
delete firstPrisoner.sentence;
//接下来，JavaScript引擎在对象上不能再找到该属性，
//必须回头去查找原型链，并在原型对象上找到该属性
// Both of these output 4
console.log( firstPrisoner.sentence );
console.log( firstPrisoner.proto.sentence );