//囚犯示例 
//1.定義原型對象 
var proto = { 
 sentence : 4, //監(jiān)禁年限 
 probation: 2 //緩刑年限 
}; 
//2.定義原型對象的構造函數(shù) 
var Prisoner = function(name, id) { 
 this.name = name; 
 this.id = id; 
}; 
//3.將構造函數(shù)關聯(lián)到原型 
Prisoner.prototype = proto; 
//4.實例化對象——采用工廠函數(shù)實例化對象 
var makePrisoner = function(name, id) { 
 //采用工廠函數(shù)實力化對象prisoner 
 var prisoner = Object.create( proto ); 
 prisoner.name = name; 
 prisoner.id = id; 
 return prisoner; 
}; 
 
var firstPrisoner = makePrisoner( 'Joe', '12A' ); 
 
//firstPrisoner.sentence在firstPrisoner對象找不到sentence屬性， 
//所以查找對象的原型并找到了Both of these output 4 
console.log( firstPrisoner.sentence ); 
console.log( firstPrisoner.__proto__.sentence ); 
//把對象的sentence屬性設置為10 
firstPrisoner.sentence = 10; 
//outputs 10 
//確定對象上的屬性值已設置為10 
console.log( firstPrisoner.sentence ); 
//但是對象的原型并沒有變化，值仍然為4 
console.log( firstPrisoner.__proto__.sentence ); 
//為了使獲取到的屬性回到原型的值，將屬性從對象上刪除 
delete firstPrisoner.sentence; 
//接下來，JavaScript引擎在對象上不能再找到該屬性， 
//必須回頭去查找原型鏈，并在原型對象上找到該屬性 
// Both of these output 4 
console.log( firstPrisoner.sentence ); 
console.log( firstPrisoner.__proto__.sentence );

xxh@xxh-E440:~/workspace$ node t6 
4 
4 
10 
4 
4 
4