//定义对象
function person(fname,lname,age,tall){
this.fname=fname;
this.lname=lname;
this.age=age;
this.tall=tall;
this.introduce=function(){
return "大家好，我的名字是"+this.fname+" "+this.lname+","+"我今年"+this.age+"岁，"+"我的身高是"+this.tall+"cm!";
}
}
//创建对象实例
var zhangsan=new person("si","li",27,173);

//动态的为对象添加属性和方法
zhangsan.eyecolor="black";
zhangsan.runspeed=function(){
return "我的速度是60km/h";
}

alert(zhangsan.introduce());
alert(zhangsan.runspeed());