Javascript 对象

1.是否所有的一切在javascript都是对象？

基本上是，除了一些特殊的元素，比如undefined,null.

2.函数是否是对象？

当然是。

3.一些JS内置的方法，例如toString（）是否是对象？

是的，toString也可以下面的方式表达

object.protorype.toString()

4.如何创建对象？

var person={
firsname:"first",
lastname:"lastname",
age:29,
changeFirstName:function(name){
this.firsname = name;
},
changeLastName: bar
}


function bar(lastname){
this.lastname = lastname;
}

上面创建js对象的方式相当于

var person = new Object();
person.firstname = "first";
person.changeFirstName= function(name){
this.firstname = name;
};

5.如何使用对象？

person.salary = 1000;
person.changeFirstName("aaa");
person.changeLastName("bbb");
console.log(person.firsname);//aaa
console.log(person["firsname"]);//aaa
console.log(person.lastname);//bb
console.log(person.age);//29
console.log(person.salary);//1000

6.如何使用构造函数创建对象

function Person2(firstname,lastname){
//var obj = new Object();// can be ommited
this.firstname = firstname; //obj.firstname
this.lastname = lastname;
　　this.changeFirstName = function(name){
this.firstname = name;
};

//return obj;//can be ommited
}

7.利用（函数）原型，完善对象

Person.prototype.changeLastName = funciton(name){
this.lastname = name;
}
//////////////////////////

var p2 = new Person2("f","l");//Person2 p2 = new Person2("f","l"); wrong
console.log(p2.firstname);//f
p2.changeFirstName("aaa");
p2.changeLastName("bbb");
console.log(p2.lastname);//bbb