是否有可能有 2 个变量指向同一个对象?(javascript) [英] Is it possible to have 2 variables pointing to the same object? (javascript)

问题描述

我试图让变量my_a"和letters.a指向同一个对象.

I'm trying to have both the variables "my_a" and letters.a point to the same object.

//i want letters.a to reference (point to) my_a, not be a copy...
//expected output should be: letters.a = c
//made variables into Objects.. but didn't help.

var my_a = new Object('a');
var my_b = new Object('b');
var letters = {'a': my_a, 'b': my_b};

$('#output').append('my_a = ' + my_a + '<br>');
$('#output').append('leters.a = ' + letters.a + '<br>');

my_a = new Object('c');

$('#output').append('my_a = ' + my_a + '<br>');
$('#output').append('letters.a = <span style="color:red">' + letters.a + '</span>');
​

看到这个小提琴:

http://jsfiddle.net/jCsUq/1/

但是正如您在输出中看到的那样，这是行不通的.

But as you can see by the output, this is not working.

有什么想法吗?这可以用 JavaScript 实现吗?

Any ideas? Is this possible with javascript?

谢谢.

推荐答案

您的问题的答案是是"，但我认为您的问题没有准确描述您想要做的事情.您希望 letters.a 引用变量my_a"，就可以使用 & 运算符在 C++ 中执行的操作而言.这在 JavaScript 中是不可能的.

The answer to your question is "yes", but I think that your question doesn't describe accurately the thing you're trying to do. What you'd like is for letters.a to be reference to the variable "my_a", in the sense of what one can do in C++ with the & operator. That's not possible in JavaScript.

在声明中:

my_a = new Object('c');

您给my_a"一个新的、不同的值.因此， letters.a 仍然指的是它所做的相同的事情，而my_a"已经改变了.没有办法让一个变量或对象属性跟踪"另一个(在 JavaScript 中).

you're giving "my_a" a new, different value. Thus, letters.a still refers to the same thing it did, while "my_a" has changed. There's no way to make a variable or object property "track" another (in JavaScript).

编辑 —实际上，我发现您可以通过为字母"的a"属性定义一个getter"来执行您正在寻找的操作，该属性返回my_a"的当前值.它需要您正在使用的 JavaScript 引擎中的该功能，但它看起来像:

edit — actually it occurs to me that you could do something like what you're looking for by defining a "getter" for the "a" property of "letters", one that returns the current value of "my_a". It'd require that feature in the JavaScript engine you're using, but it'd look something like:

var letters = {};
Object.defineProperty(letters, "a", {
  get: function() { return my_a; },
  set: function(v) { my_a = v; }
});

不幸的是，IE9 之前的 IE 不支持.这是更新后的 jsfiddle.

IE before IE9 doesn't support that unfortunately. Here's the updated jsfiddle.

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