addEventListener, "change" and option selection

I'm trying to have dynamic select list populate itself, from a single selection to start:

<select id="activitySelector">
      <option value="addNew">Add New Item</option>
</select>

and then JavaScript code we have:

addEventListener("select", addActivityItem, false); 

The problem is that various events don't fire when you have one item: not "change" because, the text is no different when you select that item; not "select" (as I have here), for a roughly similar reason, because I'm not really selecting anything because there's only one item. What is the event that should be fired here? It seems silly to list a blank item in my option list to fire the event, so I hope there is another solution. Or is that the best solution?

You need a click listener which calls addActivityItem if less than 2 options exist:

var activities = document.getElementById("activitySelector");

activities.addEventListener("click", function() {
    var options = activities.querySelectorAll("option");
    var count = options.length;
    if(typeof(count) === "undefined" || count < 2)
    {
        addActivityItem();
    }
});

activities.addEventListener("change", function() {
    if(activities.value == "addNew")
    {
        addActivityItem();
    }
});

function addActivityItem() {
    // ... Code to add item here
}

A live demo is here on JSfiddle.

The problem is that you used the select option, this is where you went wrong. Select signifies that a textbox or textArea has a focus. What you need to do is use change. "Fires when a new choice is made in a select element", also used like blur when moving away from a textbox or textArea.

function start(){
      document.getElementById("activitySelector").addEventListener("change", addActivityItem, false);
      }

function addActivityItem(){
      //option is selected
      alert("yeah");
}

window.addEventListener("load", start, false);