Cycle and Instantiate from an Array of GameObject

Hi there, I'm trying to create a function that allows (with the mouse click) to instantiate a gameObject from an array... whilst destroying the previous, in other words cycling through an array of gameObjects.

var childObject : GameObject[];
var changeObj : int = 1;

function onScrollChangeObject(){
    var newObj = Instantiate(childObject[changeObj],transform.position,transform.rotation);
    //I want the new object to be the child of this object (with the script)
    newObj.transform.parent = transform;
}   

function Update () {
    if (Input.GetButtonDown("Fire1")){
            //Is it possible to use a 'for' loop to do this cycle
        if(changeObj<2){
            changeObj++;
        } else {
            changeObj = 0;
        }
        onScrollChangeObject();
}

This instantiates from an array, but I can't work out how to Destroy the previous

Instantiate returns a reference to the instantiated object. As long as you have only one object alive at each given time you can save that reference in order to destroy it, and do something like this:

var childObject : GameObject[];
var changeObj : int = 1;
var currObjAlive: GameObject;

function onScrollChangeObject()
{
    // If there is already an object alive- destroy it
    if (currObjAlive)
        Destroy(currObjAlive);

    currObjAlive = Instantiate(childObject[changeObj],transform.position,transform.rotation);
    //I want the new object to be the child of this object (with the script)
    currObjAlive.transform.parent = transform;
}   

function Update () 
{
    if (Input.GetButtonDown("Fire1"))
    {
            //Is it possible to use a 'for' loop to do this cycle
        if(changeObj<2){
            changeObj++;
        } else {
            changeObj = 0;
        }
        onScrollChangeObject();
}

BTW - a nifty trick to use in situation where you have an array and you want to iterate over it using the index and loop is:

if (Input.GetButtonDown("Fire1"))
{
    changeObj = (changeObj + 1) % 2;
    onScrollChangeObject();
}