js函数传参

js所有函数传参都是按值传递

1>传基本参数类型：被传递的值复制给函数形参

function addMath(num){

　　num += 10;

　　return num;

}

var counts = 20;

var results = addMath(counts);

alert("count="+counts+",result="+results);

couts未改变，不是按引用传递的

2>传递obj类型

function setName(obj){

　　obj.name = "Allen";

　　obj = new Dog();

　　obj.name = "Wangcai";

　　return obj;

}

var person = new Person();

var dog = setName(person);

alert("PersonName="+person.name+",DogName="+dog.name); // allen,wangcai