var name = "Pomy";
function Per(){
  console.log("Hello "+this.name);
}
var per1 = new Per(); //"Hello undefined"
var per2 = Per();  //"Hello Pomy"

console.log(per1 instanceof Per); //true
console.log(per1.constructor === Per); //true

function Person(){}
Person.prototype.name="dwqs";
Person.prototype.age=20;
Person.prototype.sayName=function()
{
  alert(this.name);
};
var per1 = new Person();
per1.sayName(); //dwqs
var per2 = new Person();
per2.sayName(); //dwqs
alert(per1.sayName == per2.sayName); //true

alert(Person.prototype.isPrototypeOf(per2)); //true
per1.blog = "www.ido321.com";
alert(per1.hasOwnProperty("blog")); //true
alert(Person.prototype.hasOwnProperty("blog")); //false
alert(per1.hasOwnProperty("name")); //false
alert(Person.prototype.hasOwnProperty("name")); //true

function Hello(name){
  this.name = name;
}
//重写原型
Hello.prototype = {
  sayHi:function(){
    console.log(this.name);
  }
};
var hi = new Hello("Pomy");
console.log(hi instanceof Hello); //true
console.log(hi.constructor === Hello); //false
console.log(hi.constructor === Object); //true

Hello.prototype = {
  constructor:Hello,
  sayHi:function(){
    console.log(this.name);
  }
};
console.log(hi.constructor === Hello); //true
console.log(hi.constructor === Object); //false

Array.prototype.sum=function(){
  return this.reduce(function(prev,cur){
    return prev+cur;
  });
};
var num = [1,2,3,4,5,6];
var res = num.sum();
console.log(res); //21
String.prototype.capit = function(){
  return this.charAt(0).toUpperCase()+this.substring(1);
};
var msg = "hello world";
console.log(msg.capit()); //"Hello World"

var book = {
  title:"这是书名";
};
//和下面的方式一样
var book = Object.create(Object.prototype,{
  title:{
    configurable:true,
    enumerable:true,
    value:"这是书名",
    wratable:true
  }
});

var book1 = {
  title:"JS高级程序设计",
  getTitle:function(){
    console.log(this.title);
  }
};
var book2 = Object.create(book1,{
  title:{
    configurable:true,
    enumerable:true,
    value:"JS权威指南",
    wratable:true
  }
});
book1.getTitle(); //"JS高级程序设计"
book2.getTitle(); //"JS权威指南"
console.log(book1.hasOwnProperty("getTitle")); //true
console.log(book1.isPrototypeOf("book2")); //false
console.log(book2.hasOwnProperty("getTitle")); //false

function Rect(length,width){
  this.length = length;
  this.width = width;
}
Rect.prototype.getArea = function(){
  return this.width * this.length;
};
Rect.prototype.toString = function(){
  return "[Rect"+this.length+"*"+this.width+"]";
};
function Square(size){
  this.length = size;
  this.width = size;
}
//修改prototype属性
Square.prototype = new Rect();
Square.prototype.constructor = Square;
Square.prototype.toString = function(){
  return "[Square"+this.length+"*"+this.width+"]";
};
var rect = new Rect(5,10);
var square = new Square(6);
console.log(rect.getArea()); //50
console.log(square.getArea()); //36

Square.prototype.toString = function(){
  var text = Rect.prototype.toString.call(this);
  return text.replace("Rect","Square");
}