javascript函数传参是传值还是传引用？

Question

function changeStuff(num, obj1, obj2)

{

    num = num * 10;

    obj1.item = "changed";

    obj2 = {item: "changed"};

}

var num = 10;

var obj1 = {item: "unchanged"};

var obj2 = {item: "unchanged"};

changeStuff(num, obj1, obj2);

console.log(num);   // 10

console.log(obj1.item);    // changed

console.log(obj2.item);    // unchanged

为什么是这个情况？

Answer 1

js所有的传递都是值传递