Is it possible to overwrite an object after being passed?

Question

See the following example:

var foo = { bar : 0 };

function modify(obj)
{
    obj = {};
}

modify(foo);

console.log(foo);

My first object in the global scope remains unchanged. Because the function did not replace the object but a copy of the reference.

So my question is simple. Does anyone know of a work-around way, or are there ECMAScript features in currently development or have there been attempts to make this possible at all?

Thanks.

You aren't passing foo as argument of your function. By the way, you don't want to overwrite stuff in this way. Read about stateless functions — Fez Vrasta, Jun 04 '16 at 10:40
You're defining `modify` with one parameter, but calling it with none. Did you mean to call it with `foo`? — , Jun 04 '16 at 10:41

score 1 · Answer 1 · answered Jun 04 '16 at 10:42

You can't change the binding of the variable that you were called with. But since you receive a reference to the same object, you can modify the object itself. So you can remove all the properties:

function modify(obj) {
  Object.keys(obj).forEach(function(k) {
    delete obj[k];
  });
}

var foo = { a: 3 };
console.log(foo);
modify(foo);
console.log(foo);

Is it possible to overwrite an object after being passed?

1 Answers1