为对象分配其他内容时，为什么不通过引用传递此对象？ [英] Why isn't this object being passed by reference when assigning something else to it?

问题描述

我知道在JS中，对象是通过引用传递的，例如：

I know that in JS, objects are passed by reference, for example:

function test(obj) {
    obj.name = 'new name';
}

var my_obj = { name: 'foo' };
test(my_obj);
alert(my_obj.name); // new name

但为什么以下不起作用：

But why doesn't the below work:

function test(obj) {
    obj = {};
}

var my_obj = { name: 'foo' };
test(my_obj);
alert(my_obj.name); // foo

我已将对象设置为 {} （空）但它仍然说 foo 。

I have set the object to {} (empty) but it still says foo.

任何人都可以解释这背后的逻辑吗？ / p>

Can any one explain the logic behind this?

推荐答案

如果您熟悉指针，那么您可以采用类比。你实际上是在传递一个指针，所以 obj.someProperty 会取消引用该属性并实际覆盖它，而只是覆盖 obj 会杀死指针而不会覆盖对象。

If you are familiar with pointers, that's an analogy you can take. You're actually passing a pointer, so obj.someProperty would dereference to that property and actually override that, while merely overriding obj would kill off the pointer and not overwrite the object.

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