1. 动态添加属性，方法

var object = new Object();

object.name = "name";

object.age = 19;

>>>{name: "name", age: 19}

object.fun = function(){

　　console.log("这是一个测试")

}

object.fun()

2.修改属性

object.name=”tom”;
object.alert=function(){
alert(“hello,”+this.name);
}

3.删除属性

object.name = undefined

object.age = undefined