Javascript中的原始类型/引用类型 [英] primitive types / reference types in Javascript

问题描述

我的假设是Javascript中存在原始类型和引用类型。在日常工作中，我从来没有对我产生过影响，但我刚刚开始更多的JS，并希望更新我的'思考'。换句话说，我会打赌20美元，以下将返回68

I have lived under the assumption that there are primitive types and reference types in Javascript. On a day-to-day basis, I've never had this impact me but I was just starting to a lot more JS and wanted to update my 'thinking'. In other words, I would have betted $20 that the following would return 68

var my_obj = {};
var tmp_obj = {};

tmp_obj.my_int = 38;
my_obj.tmp_val = tmp_obj.my_int;
tmp_obj.my_int = 68;

alert('68 means reference, 38 means primitve: ' + my_obj.tmp_val);

但它返回38.

< img src =https://i.stack.imgur.com/Q8JZj.pngalt =在此处输入图像说明>

所有数字实例都是原始的类型即使它们存在于引用类型的上下文中？如果你，我真的很惊讶，发现这种奇怪的行为（并且会出20美元）。或者我的例子没有证明我认为它是什么？

Are all instances of numbers primitive types even if they exist in the context of a reference type? If y, I'm really surprised and find that odd behavior(and would be out $20). Or is my example not demonstrating what I think it is?

提前thx

UPDATE＃ 1

哇，谢谢所有答案。这是一个微小的变化，这对我的理解很有帮助：

Wow, thx for all the answers. Here's a slight change which helps me a lot in understaning:

var my_obj={};
var tmp_obj={};
var my_obj_2=tmp_obj;
tmp_obj.my_int=38;
my_obj.tmp_val=tmp_obj.my_int;
tmp_obj.my_int=68
alert('68 means reference, 38 means primitve: ' + my_obj.tmp_val);   // 38
alert('68 means reference, 38 means primitve: ' + my_obj_2.my_int);  // 68
my_obj_2.my_int=78;
alert(tmp_obj.my_int); // tmp_obj is now 78 ie two way

推荐答案

你的例子如果您有

     my_obj = tmp_obj;

然后，所有属性都会指向相同的引用，因为只有一个对象。

Then, all the properties would point to the same reference since there would only be one object.

但是当你写的时候

     my_obj.tmp_val = tmp_obj.my_int;

然后 my_obj.tmp_val 将取值它存储在 tmp_obj.my_int 中，但不会在2个对象之间创建新的引用。

then my_obj.tmp_val will take the value that's stored in tmp_obj.my_int but that doesn't create a new reference between the 2 objects.

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