合并 Javascript 对象和所有指向它们的引用 [英] Merge Javascript Objects and All References Pointing at Them

问题描述

在javascript中，引用对象的变量会被传递一个引用副本".我正在努力解决这个概念，因为它涉及合并两个对象，以及对这些对象的引用的影响.尝试使用下划线的扩展，取以下(咖啡脚本)代码:

In javascript, variables referring to objects are passed a "copy of the reference". I am struggling with this concept as it relates to merging two objects, and the effect on the references to those objects. Attempting to use underscore's extend, take the following (coffeescript) code:

a = {
    id: 1
    type: "cat"
    name: "Angry"
}
b = {
    id: 1
    type: "dog"
    owner: "Bill"
}

c = a
d = c
e = b


_.extend(a, b)

b = a

d.home = "Nashville"

console.log(a) //Object {id: 1, type: "dog", name: "Angry", owner: "Bill", home: "Nashville"} 
console.log(b) //Object {id: 1, type: "dog", name: "Angry", owner: "Bill", home: "Nashville"}
console.log(c) //Object {id: 1, type: "dog", name: "Angry", owner: "Bill", home: "Nashville"}
console.log(d) //Object {id: 1, type: "dog", name: "Angry", owner: "Bill", home: "Nashville"}
console.log(e) //Object {id: 1, type: "dog", owner: "Bill"}

正如我们所见，下划线并没有合并"对象.相反，下划线将 b 引用的对象的属性设置在 a 引用的对象上.之后，当我们替换b持有的引用指向a引用的对象时，e继续持有该对象的引用最初由 b 引用.这是因为 e 没有分配给 b 的引用，而是分配给 b 的引用副本.类似地，d 持有一个引用，不是对 c 而是对由 a 引用的对象.

As we can see, underscore did not 'merge' the objects. Instead, what has happened is that underscore set the attributes of the object referred to by b on the object referred to by a. Later, when we replace the reference held by b to point at the object referred to by a, e continues to hold a reference to the object originally referred to by b. This is because e was not assigned a reference to b, but rather a copy of the reference held by b. Similiarly, d holds a reference, not to c but to the object referred to by a.

我想找到一种真正合并两个对象的方法，以便对两个对象的所有引用都指向一个目标.这在 Javascript 中是可能的，还是由于 Javascript 的对象传递结构而无法执行此操作?

I would like to find a way to truly merge the two objects, so that all references to both objects point at a single destination. Is this possible in Javascript, or am I precluded from doing this as a result of Javascript's object passing structure?

推荐答案

我想找到一种真正合并两个对象的方法，以便对两个对象的所有引用都指向一个目标.这在 Javascript 中是可能的，还是由于 Javascript 的对象传递结构而无法执行此操作?

I would like to find a way to truly merge the two objects, so that all references to both objects point at a single destination. Is this possible in Javascript, or am I precluded from doing this as a result of Javascript's object passing structure?

如果不更改引用，这是不可能的，即可以访问所有变量并使用新的引用值重新分配它们 - 在您的情况下，e = b 就像您所做的 b= 一个.

That's impossible without changing the references, i.e. having access to all the variables and re-assigning them with the new reference value - in your case, e = b just as you did b = a.

要获得预期的结果，您可能需要执行 _.extend(a, b);_.extend(b, a); 使它们具有相同的属性 - 但是它们是两个不同的对象.

To get the expected result, you might want to do _.extend(a, b); _.extend(b, a); so that they have the same properties - however they stay two different objects.

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