Firing an input event only when the field has a value

So, with this one I want to only react to the event when the field has changed (the standard input event) but NOT when it has been changed to become empty.

by Matt Rummler

HTML

<div id="overarchingDiv">
<form id="testForm0">
  <input type="text" id="field1">
</form>
<form id="testForm1">
  <input type="text" id="field1" class='theOneField'>
</form>
<form id="testForm2">
  <input type="text" id="field1">
</form>
    <button id="populate fields button" class='thatOneButton'>
        Populate All Fields
    </button>
</div>

JavaScript

var topLevel = document.getElementById('overarchingDiv');
var finalField = topLevel.getElementsByClassName('theOneField')[0];
var buttonOne = topLevel.getElementsByClassName('thatOneButton')[0];
finalField.addEventListener("input", function(e){showAlert(e,finalField);}, false);
buttonOne.addEventListener("click", function(e){populateOneOrMoreFields(e);}, false);
//// SUPPORTING FUNCTION ////
Object.forEach=(function forEach()
{
  return function(obj,fn)
  {
    if(obj.length)
    {
      for (var i = 0, ol = obj.length, v = obj[0]; i < ol && fn(v, i) !== false; v = obj[++i]);
    }
	else
    {
      for (var p in obj) if (fn(obj[p], p) === false) break;
    }
  };
})(this);
//// primary function(s) ////
function populateOneOrMoreFields(event,inputValue)
{
    inputValue=inputValue || 1;
    var inputEvent = new Event('input');//,{bubbles:false,cancelable:false});
    var inputElementsCollection = document.getElementsByTagName('input');
//    var inputElementEventTarget=document.getElementById('');
    Object.forEach(inputElementsCollection, function(inputElement, key)
    {
        inputElement.value=inputValue;
//        alert('The class of the current element is: '+inputElement.className);
        if(inputElement.className=='theOneField')
        {
        	inputElement.dispatchEvent(inputEvent);
        }
//        alert('The new value of the current element is: '+inputElement.value);
    });
}

function showAlert(e,fieldOne)
{
    if(fieldOne.value)
    {
    	alert("Event is called because the input changed! The following is the type of event: " + e.type);
    }
}