functioninstance_of(L, R){//L 表示左表达式，R 表示右表达式
varO = R.prototype;// 取 R 的显示原型
 L = L.__proto__; // 取 L 的隐式原型
while(true) {
if(L ===null)
returnfalse;
if(O === L)// 这里重点：当 O 严格等于 L 时，返回 true
returntrue;
 L = L.__proto__; 
 } 
}

functionFather(){
this.name ="father";
this.friends = ['aaa','bbb'];
}
functionSon(){
}
Son.prototype = newFather();
Son.prototype.constructor = Son;

vars1 =newSon();
vars2 =newSon();

console.log(s1.name);// father
console.log(s2.name);// father
s1.name = "son";
console.log(s1.name);// son
console.log(s2.name);// father

console.log(s1.friends);// ["aaa", "bbb"]
console.log(s2.friends);// ["aaa", "bbb"]
s1.friends.push('ccc','ddd');
console.log(s1.friends);// ["aaa", "bbb", "ccc", "ddd"]
console.log(s2.friends);// ["aaa", "bbb", "ccc", "ddd"]

functionFather(name,friends){
this.name = name;
this.friends = friends;
}
Father.prototype.getName = function(){
returnthis.name;
};

functionSon(name){
// 注意： 为了确保 Father 构造函数不会重写 Son 构造函数的属性，请将调用 Father 构造函数的代码放在 Son 中定义的属性的前面。
 Father.call(this,name,['aaa','bbb']);

this.age =22;
}

vars1 =newSon('son1');
vars2 =newSon('son2');

console.log(s1.name);// son1
console.log(s2.name);// son2

s1.friends.push('ccc','ddd');
console.log(s1.friends);// ["aaa", "bbb", "ccc", "ddd"]
console.log(s2.friends);// ["aaa", "bbb"]

// 子类实例无法访问父类原型中的方法
s1.getName(); // TypeError: s1.getName is not a function
s2.getName(); // TypeError: s2.getName is not a function

functionFather(name,friends){
this.name = name;
this.friends = friends;
}
Father.prototype.money = "100k $";
Father.prototype.getName = function(){
console.log(this.name);
};

functionSon(name,age){
// 继承父类的属性
 Father.call(this,name,['aaa','bbb']);

this.age = age;
}

// 继承父类原型中的属性和方法
Son.prototype = newFather();
Son.prototype.constructor = Son;

Son.prototype.getAge = function(){
console.log(this.age);
};

vars1 =newSon('son1',12);
s1.friends.push('ccc');
console.log(s1.friends);// ["aaa", "bbb", "ccc"]
console.log(s1.money);// 100k $
s1.getName(); // son1
s1.getAge(); // 12

vars2 =newSon('son2',24);
console.log(s2.friends);// ["aaa", "bbb"]
console.log(s2.money);// 100k $
s2.getName(); // son2
s2.getAge(); // 24

functionobj(o){
functionF(){}
 F.prototype = o;
returnnewF();
}
varperson1 = {
 name: "percy",
 friends: ['aaa','bbb']
};
varperson2 = obj(person1);
person2.name = "zyj";
person2.friends.push('ccc');

console.log(person1.name);// percy
console.log(person2.name);// zyj
console.log(person1.friends);// ["aaa", "bbb", "ccc"]
console.log(person2.friends);// ["aaa", "bbb", "ccc"]
ECMAScript 5 通过新增 Object.create() 方法规范化了原型式继承。在传入一个参数的情况下， Object.create() 和 obj() 方法的行为相同。

varperson1 = {
 name: "percy",
 friends: ['aaa','bbb']
};
varperson2 =Object.create(person1);
person2.name = "zyj";
person2.friends.push('ccc');

console.log(person1.name);// percy
console.log(person2.name);// zyj
console.log(person1.friends);// ["aaa", "bbb", "ccc"]
console.log(person2.friends);// ["aaa", "bbb", "ccc"]

functionobj(o){
functionF(){}
 F.prototype = o;
returnnewF();
}
functioncreatePerson(original){// 封装继承过程
varclone = obj(original);// 创建对象
 clone.showSomething = function(){// 增强对象
console.log("Hello world!");
 };
returnclone;// 返回对象
}

varperson = {
 name: "percy"
};
varperson1 = createPerson(person);
console.log(person1.name);// percy
person1.showSomething(); // Hello world！

functionFather(name,friends){
this.name = name;
this.friends = friends;
}
Father.prototype.money = "100k $";
Father.prototype.getName = function(){
console.log(this.name);
};

functionSon(name,age){
// 继承父类的属性
 Father.call(this,name,['aaa','bbb']);// 第二次调用 Father() ， 实际是在 new Son() 时才会调用

this.age = age;
}

// 继承父类原型中的属性和方法
Son.prototype = newFather();// 第一次调用 Father()
Son.prototype.constructor = Son;

functionobj(o){
functionF(){}
 F.prototype = o;
returnnewF();
}
functioninheritPrototype(son,father){
varprototype = obj(father.prototype);// 创建对象
 prototype.constructor = son; // 增强对象
 son.prototype = prototype; // 返回对象
}
functionFather(name,friends){
this.name = name;
this.friends = friends;
}
Father.prototype.money = "100k $";
Father.prototype.getName = function(){
console.log(this.name);
};

functionSon(name,age){
// 继承父类的属性
 Father.call(this,name,['aaa','bbb']);

this.age = age;
}

// 使用寄生式继承继承父类原型中的属性和方法
inheritPrototype(Son,Father);

Son.prototype.getAge = function(){
console.log(this.age);
};

vars1 =newSon('son1',12);
s1.friends.push('ccc');
console.log(s1.friends);// ["aaa", "bbb", "ccc"]
console.log(s1.money);// 100k $
s1.getName(); // son1
s1.getAge(); // 12

vars2 =newSon('son2',24);
console.log(s2.friends);// ["aaa", "bbb"]
console.log(s2.money);// 100k $
s2.getName(); // son2
s2.getAge(); // 24