instantiate random object in Specified positions?

hello
I have 14 different cubes and want to randomly put them in specified 15 positions one of that positions should be empty.
how can I do that!?
please javascript
thanks

You can put all your possible positions in a list, then choose one randomly, spawn the cube there, and remove it from the list. Until one remains:

public Vector3[] positions = new Vector3[15]; 
public GameObject cubePrefab;

public void Start() {
    List<Vector3> positionsList = new List<Vector3>(positions); // convert possible positions to list

    // iterate as long as more than one position remains
    while (positionsList.Count > 1) {
        int chosenPositionIndex = Random.Range(0, positionsList.Count); // choose random position from list
        GameObject.Instantiate(cubePrefab, positionsList[chosenPositionIndex], Quaternion.identity); // create a cube at position
        positionsList.RemovaAt(chosenPositionIndex); // remove position from list
    } 
}

Be sure to put the possible positions in the inspector, and the prefab for the cube.