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/*
Examples From
JavaScript: The Definitive Guide, Fourth Edition
Legal matters: these files were created by David Flanagan, and are
Copyright (c) 2001 by David Flanagan. You may use, study, modify, and
distribute them for any purpose. Please note that these examples are
provided "as-is" and come with no warranty of any kind.
David Flanagan
*/
<html>
<head>
<script>
// This function is passed a DOM Node object and checks to see if that node
// represents an HTML tag: i.e., if the node is an Element object. It
// recursively calls itself on each of the children of the node, testing
// them in the same way. It returns the total number of Element objects
// it encounters. If you invoke this function by passing it the
// Document object, it traverses the entire DOM tree.
function countTags(n) { // n is a Node
var numtags = 0; // Initialize the tag counter
if (n.nodeType == 1 /*Node.ELEMENT_NODE*/) // Check if n is an Element
numtags++; // Increment the counter if so
var children = n.childNodes; // Now get all children of n
for(var i=0; i < children.length; i++) { // Loop through the children
numtags += countTags(children[i]); // Recurse on each one
}
return numtags; // Return total number of tags
}
</script>
</head>
<!-- Here's an example of how the countTags() function might be used -->
<body onload="alert('This document has ' + countTags(document) + ' tags')">
This is a <i>sample</i> document.
</body>
</html>
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