是否可以通过引用传递或访问实际对象？

Question

I understand that javascript is always "Pass-by-value". Even when when assigning an object, it passes a value which is a reference to the object.

1: var obj1 = {name: "bob"};
2: var obj2 = obj1;
3: obj2.name = "joe";
4: console.log(obj1.name);    // output: "joe"
5: obj2 = {name: "ron"};
6: console.log(obj1.name);    // output: "joe"

On line 4, both obj1 and obj2 contain a reference to the same object, and that we are able to manipulate that object through both variables. But line 5 sets obj2 to refer to a new object. now obj1 and obj2 have references to 2 different objects. This all makes sense so far.

My question is this: is there any way to access the object itself and not just references to it? So that instead of simply manipulating the object we can change it to a whole new object and any variables that referenced it would now reference the new object? something like this:

var obj1 = {name: "bob"};
var obj2 = obj1;
var actualObject = GetActualObjectReferencedBy(obj2);
actualObject = new Date();
console.log(obj1)      // output: the current date;
console.log(obj2)      // output: the current date;

So that actualObject is just that. the actual object that everything is referring to, not just a reference. And making ANY changes to it doesn't break the references.

Here is an example of why I want to do this:

function Person(n){
  this.name = n;
}
function attachProxies(){
  for(var i = 0; i < arguments.length; i++){
    var actualObject = GetActualObject(arguments[i]);
    actualObject = new Proxy(actualObject, {
      get: function(obj, prop){ return "I'm " + obj[prop]; };
    });
  }
}

var guy1 = new Person("bob");
var guy2 = new Person("joe");
var guy3 = new Person("rom");
attachProxies(guy1, guy2, guy3);

console.log(guy2.name);    // output: "I'm joe"

The closest thing I can figure is this:

function attachProxies(obj){
  return new Proxy(obj, {
    get: function(obj, prop){return "I'm "+obj[prop];};
  });
}
var guy1 = new Person("bob");
var guy2 = new Person("joe");
var guy3 = new Person("rom");
guy1 = attachProxies(guy1);
guy2 = attachProxies(guy2);
guy3 = attachProxies(guy3);

But that's much more limited and repetitive.

I've tried looking around but I can't seem to find any way of doing this. If it's not possible, please help me understand the reasoning.

Edit:

I don't believe this counts as a duplicate because I acknowledge in the setup to my question that javascript passes by value. The supposed duplicate only states that but does not answer my question of whether there is any way access the object.

Answer 1

No, this is not possible. You cannot get access to the memory where the object's contents are stored and replace them with different contents taken from another object.

Well, you can do that, but in a limited way. You can change the object's contents, which are mainly the object's properties , by simply assigning them new values. You can even swap out its prototype chain with Object.setPrototypeOf . (Assuming that the object isn't frozen or otherwise non-configurable).

But what you absolutely cannot do is swap out the object for an object of a different internal type, such as your plain object-literal object for a Date instance of even a Proxy . This is fundamentally impossible.

Your "the closest thing" solution is indeed the closest thing you can do, and it involves assigning new reference values to all the places (in your case, variables) that stored the old reference. You can however make it less repetitive if your wrapper function supports the syntax

[guy1, guy2, guy3] = attachProxies(guy1, guy2, guy3);