Defining a getter for document.cookie

Question

I would like to know how to define a getter for default objects like document.cookie.

document.__defineGetter__("cookie", function(newv) {
   console.log('accessing cookie'); 
  //what to return here??
 });

Returning document.cookie obviously causes a recursion.
Thanks

If you're using a browser that can successfully call `__defineGetter__`, you'd be better off using `localStorage`. — zzzzBov, Aug 19 '13 at 15:12
[`__defineGetter__`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineGetter) non-standard, deprecated — Emissary, Aug 19 '13 at 15:12
I want to write my own logic everytime some specific properties of the DOM are being accessed. — everconfusedGuy, Aug 19 '13 at 15:15

score 3 · Answer 1 · answered Nov 25 '13 at 21:35

Try something like this -

var old_cookie = document.cookie;

Object.defineProperty(document, 'cookie', {
    get: function() {
        console.log('Getting cookie');
        return this._value;
    },
    set: function(val) {
        console.log('Setting cookie', arguments);
        this._value = val;
        return this._value;
    }
});

document.cookie = old_cookie;

When you add getters/setters to the cookie property, it wipes away the value because descriptors cannot have both accessors and a value, so you have to save the old cookie value and re-assign it after you define the accessors.

score 0 · Answer 2 · edited Jun 20 '20 at 09:12

0

Try this:

Chrome

var desc = Object.getOwnPropertyDescriptor(document, 'cookie');

return desc.value;

However, I'm not sure if this will reflect updates.

Firefox, IE 10

var getter = Object.getOwnPropertyDescriptor(Object.getPrototypeOf(document), 'cookie').get.bind(document)

return getter();

This should work perfectly.

edited Jun 20 '20 at 09:12

Community

1
1

answered Aug 19 '13 at 15:13

SLaks

868,454
176
1,908
1,964

Defining a getter for document.cookie

2 Answers2

Chrome

Firefox, IE 10

Linked