Week 4 homework #2 on the Theory of the DOM

dom2.html

<script type="text/javascript">
function walkTheDOM(node, func) {
        func(node); 
        node = node.firstChild; 
        while (node) { 
            walkTheDOM(node, func); 
            node = node.nextSibling; 
        } 
    } 
function countTextNodes() {
   var sum = 0;
   function count (node) {
      if (node.nodeType == 3) // TEXT_NODE
      sum++;
      }
      var root = document.documentElement;
      walkTheDOM(root, count);
      var foo = document.getElementById("foo");
      var newElement = document.createTextNode ("There are " + sum + " text nodes");
      foo.appendChild(newElement);
}

</script>
<p id="foo">
<button type="button" onclick="countTextNodes()">Count Text Nodes</button> 
</p>