Javascript 为什么嵌套对象不通过引用传递？

关于这个话题有数百万个问题，但我找不到对这种情况的解释：

const obj = { nObj: {a: 1}};

const obj2 = obj.nObj; // the value of obj2 is an object, not a primitive

obj.nObj = {b: 2};

console.log(obj2) // outputs {a: 1}

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为什么会发生这种情况？

请注意，值是通过引用传递的，而不是键

以下是评论中的解释

// There are 2 references here one being referenced by obj and the other is by obj.nObj
const obj = { nObj: {a: 1}};

// obj2 also starts pointing to the same reference as obj.nObj
const obj2 = obj.nObj; // the value of obj2 is an object, not a primitive

// obj.nObj now points to a different reference
obj.nObj = {b: 2};

// obj2 continues to hold the original reference, hence, remains unchanged.
console.log(obj2) // outputs {a: 1}

谢谢你：）。。。。