js按值传递和按引用传递

1.按值传递：string、num、bool

function test1(num){
return num+1;
}
var i=7;
console.log(test1(i));   //8
console.log("outer i:"+i);  //7不会改变函数外边的值

2.按引用传递：arr、obj

function test2(obj){
obj.age=888;
return obj;
}
var obj={name:"wangba"}
console.log(test2(obj));  //{name:'wangba',age:888}
for(var i in obj){   //name:'wangba'   age:8888 修改了函数外边的值
console.log(i+":"+obj[i]);
}