function Person(props){
this.name=props.name||'匿名';
this.age=props.age||20;
this.friends=props.friends||'无';
}
Person.prototype.sayhi=function(){
console.log("你好！"+this.name);
}
Person.prototype.addFriend=function(newf){
this.friends.push(newf);
console.log(this.friends);
}
function createPerson(props) {
  return new Person(props || {});
}

var xiaozhang=createPerson({
name:'小张',
age:22,
friends:["小李","小王"]
});
xiaozhang.sayhi();//你好！小张
xiaozhang.addFriend('James');//["小李", "小王", "James"]