js精要之构造函数

// 枚举对象

  var obj = {}
obj.name = "bob";
obj.age = "";
obj.sex = "boy";
console.log(obj);
for(var sum in obj){
// console.log(sum);
}

// 构造函数 sayName自有方法

   function Person(name){
this.name = name;
this.sayName = function(){
console.log(this.name);
}
}
var person1 = new Person("aaa");
var person2 = new Person("bbb");
console.log(person1.name); // aaa
console.log(person2.name); // bbb
person1.sayName(); // aaa
person2.sayName(); // bbb

// 每个函数都带有一个prototype属性  sayName1 为原型方法

  function Person1(name){
this.name = name;
}
Person1.prototype.sayName1 = function(){
console.log(this.name);
}
var person1a = new Person1("aaa-v");
var person2a = new Person1("bbb-v");
console.log(person1a.name); // aaa-v
console.log(person2a.name); // bbb-v
person1a.sayName1(); // aaa-v
person2a.sayName1(); // bbb-v

// 鉴别一个原型属性

   function hasPrototypeProperty(name,object){
return name in object && !object.hasOwnProperty(name);
}
var book = {
title:"this is book!"
}
console.log(hasPrototypeProperty("title",book)); //false
console.log(hasPrototypeProperty("hasOwnProperty",book)); //true
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