Appending List Items

index.html

<script type="text/javascript">
  window.onload=function() {
    var el = document.getElementById('postComment').addEventListener('click', registerClickHandler);

    function registerClickHandler() {
      var inputValue = document.getElementById('comment').value;
      var list = document.getElementById('commentList');

      if (inputValue) {
        var listNode = document.createElement("LI");
        var textNode = document.createTextNode(inputValue);
        listNode.appendChild(textNode);
        list.appendChild(listNode);
        document.getElementById('comment').value = "";
      }
    }
  }
</script>

<ul id='commentList'>
</ul>
<form>
  <input type='text' id='comment'/>
  <input type='button' id='postComment' value='Post'/>
</form>