Implementing Array functions (indexOf, lastIndexOf, removeDuplicates...)

Hi,

I'm trying to implement some functions to manipulate Arrays more easily, like I would do with other programming languages (Array.indexOf() does exist in Javascript, but seems to be missing from ExtendScript).

First, I tried to add those functions using Array.prototype; here is what I did for two of those functions:

Array.prototype.indexOf = function (value)
        {
          for (var i = 0;i<this.length;i++)
            {
                if (this == value) return i;
            }
            return -1;
        }
       
Array.prototype.removeDuplicates = function ()
        {
            var removed = [];
            for (var i = 0;i<this.length-1;i++) {
                    for (var j=i+1;j<this.length;j++) {
                        if (this == this) {               
                            removed.push(this.splice(j,)1);
                        }
                    }
                }
                return removed;
        }

It seemed to work well, but I found out that it breaks this kind of loop:

for (var i in array) {
     alert(array);
     }

The loop goes through array values, and continues beyond array.length with the functions added to the prototype.

As explained here, I found a workaround, using Object.defineProperty() instead of implementing functions in Array.proptotype

Object.defineProperty(Array.prototype, "indexOf", {
  enumerable: false,
  value: function(value) {
      for (var i = 0;i<this.length;i++)
            {
                if (this == value) return i;
            }
            return -1;
    }
});

But..... Object.defineProperty() is missing in ExtendScript too!

I don't know what to try next... Any idea?

Thanks!