Using XPath in JavaScript (Mozilla based) (See related posts)

The following JavaScript code uses XPath to select a specific element. Note: This code works for Firefox, but Internet Explorer has it's own implementation of XPath. see Introduction to using XPath in JavaScript [mozilla.org]

doc (xml document)

   1  
   2  <codes>
   3    <codex value='bQ' index='Q'/>
   4    <codex value='S' index='R'/>
   5    <codex value='PU' index='S'/>
   6    <codex value='ji' index='T'/>
   7    <codex value='0' index='U'/>
   8    <codex value='33' index='V'/>
   9    <codex value='A' index='W'/>
  10    <codex value='tO' index='X'/>
  11    <codex value='fW' index='Y'/>
  12    <codex value='P' index='Z'/>
  13    <codex value='4h' index='a'/>
  14    <codex value='B' index='b'/>
  15    <codex value='m' index='c'/>
  16    <codex value='qf' index='d'/>
  17    <codex value='uJ' index='e'/>
  18  </codes>

Assuming the doc object below contains the XML data from above.

   1  
   2  var nodesSnapshot = doc.evaluate("codes/codex[@index='a']", doc, null, XPathResult.
   3    UNORDERED_NODE_SNAPSHOT_TYPE, null );
   4  node = nodesSnapshot.snapshotItem(0);
   5  msg = "The secret code for '" + node.getAttribute('index') + "' is " + node.getAttribute('value');
   6  alert(msg);

output (value from the alert box)

   1  
   2  "The secret code for 'a' is 4h"

see also: Reading an XML file using JavaScript