unique object identifier in javascript

Question

I need to do some experiment and I need to know some kind of unique identifier for objects in javascript, so I can see if they are the same. I don't want to use equality operators, I need something like the id() function in python.

Does something like this exist ?

Answer 1

Update My original answer below was written 6 years ago in a style befitting the times and my understanding. In response to some conversation in the comments, a more modern approach to this is as follows:

    (function() {
        if ( typeof Object.id == "undefined" ) {
            var id = 0;

            Object.id = function(o) {
                if ( typeof o.__uniqueid == "undefined" ) {
                    Object.defineProperty(o, "__uniqueid", {
                        value: ++id,
                        enumerable: false,
                        // This could go either way, depending on your 
                        // interpretation of what an "id" is
                        writable: false
                    });
                }

                return o.__uniqueid;
            };
        }
    })();
    
    var obj = { a: 1, b: 1 };
    
    console.log(Object.id(obj));
    console.log(Object.id([]));
    console.log(Object.id({}));
    console.log(Object.id(/./));
    console.log(Object.id(function() {}));

    for (var k in obj) {
        if (obj.hasOwnProperty(k)) {
            console.log(k);
        }
    }
    // Logged keys are `a` and `b`