Is there any kind of hash code function in JavaScript?

Question

Basically, I'm trying to create an object of unique objects, a set. I had the brilliant idea of just using a JavaScript object with objects for the property names. Such as,

set[obj] = true;

This works, up to a point. It works great with string and numbers, but with other objects, they all seem to "hash" to the same value and access the same property. Is there some kind of way I can generate a unique hash value for an object? How do strings and numbers do it, can I override the same behavior?

Answer 1

If you want a hashCode() function like Java's in JavaScript, that is yours:

String.prototype.hashCode = function(){
    var hash = 0;
    for (var i = 0; i < this.length; i++) {
        var character = this.charCodeAt(i);
        hash = ((hash<<5)-hash)+character;
        hash = hash & hash; // Convert to 32bit integer
    }
    return hash;
}

That is the way of implementation in Java (bitwise operator).

Please note that hashCode could be positive and negative, and that's normal, see HashCode giving negative values. So, you could consider to use Math.abs() along with this function.