对象

拥有一些属性拥有一些方法的这样一个集合

创建对象

var car = new Object();
var car = {};

属性和方法

var car = {
   color:"red",
   run:function(){
       alert("run")
   }
};
car.color;    //"red"
car.run();    //alert("run")
car["color"]; //"red"
car["run"](); //alert("run")

增加属性和方法

var car = {
    color:"red",
    run:function(){
        alert("run")
    }
};
car.type = "suv";
car.stop = function(){
    alert("stop")
};

修改属性和方法

var car = {
    color:"red",
    run:function(){
        alert("run")
    }
};
car.color = "white";
car.run = function(){
    alert("run2")
};

删除属性和方法

var car = {
    color:"red",
    run:function(){
        alert("run")
    }
};
delete car.color;
car.color //undefined

obj.constructor 某个对象是由哪个函数方法构建出来的

var car = {
    color:"red",
    run:function(){
        alert("run")
    }
};
car.constructor;//Object

var num = new Number(123);
num.constructor;//Number 获取某个对象的构造函数

obj.toString()把一个对象转成字符串

var num = new Number(123);
num.toString();//"123"

obj.valueOf()获取对象的原始值

var num = new Number(123);
num.valueOf() //123

obj.hasOwnproperty()这个对象自己所拥有的那个属性，返回布尔值

var car = {
    color:"red",
    run:function(){
        alert("run")
    }
};
car.hasOwnProperty("color") //true
car.hasOwnProperty("logo") //false