Error parsing XML file in JavaScript

Question

I'm trying to parse a simple XML file but I'm having trouble trying to obtain a value I need. The current error message I'm getting says node is not an object or is null. I'm testing on both I.E. 6, 7, FF 2,3

Here's the XML file:

<bookstore>
  <appSettings>
    <add key="myKey" value="myTargetValue"/>
  </appSettings>
</bookstore>

Here's the script I'm trying to use:

<html>
  <head>
    <title></title>
  </head>
  <script type="text/javascript">
    if (window.XMLHttpRequest)
    {
      xhttp = new window.XMLHttpRequest()
    }
    else
    {
      xhttp = new ActiveXObject("Microsoft.XMLHTTP")
    }
    xhttp.open("GET","test.xml",false);
    xhttp.send("");
    xmlDoc=xhttp.responseXML;
    alert(xmlDoc.xml)

    var xpath = "/bookstore/appSettings/add[@key='myKey']";
    var node  = xmlDoc.selectSingleNode(xpath);
    alert(node.getAttribute("value"));    
  </script>
  <body>
  </body>
</html>

Please advise. Thank you.

your XPath returns: <add key="myKey" value="myTargetValue"/> Is this what you expect? — dnagirl
– dnagirl, Commented Oct 20, 2009 at 13:44

Matt Ball · Accepted Answer · 2009-10-20 13:56:46Z

1

I would strongly advise using a library such as jQuery to make your life easier - no more document.getElementById()-ing! In jQuery you can just do:

$.ajax({
    type: 'GET',
    url: 'test.xml',
    dataType: 'xml',
    success: processXml
});

function processXml(xml)
{
    xml = $(xml);
    var value = xml.find('bookstore appSettings add[key=myKey]').attr('value');
    alert(value);
}

Edit: I'm not that familiar with XPath, so I figured I would explain the find() call in case I misread what you're trying to select from the XML. jQuery uses CSS selector syntax. So, that find() will select add nodes that have the key attribute equal to myKey, which are descendant elements of appSettings, which descend from bookstore elements.

edited Oct 20, 2009 at 13:56

answered Oct 20, 2009 at 13:48

Matt Ball

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3 Comments

Rod Over a year ago

Thanks everyone for the help... Matt, any ideas why it's not working on IE6?

Rod Over a year ago

Nevermind, I think it's getting blocked by my browser security, thanks again for the help.

Matt Ball Over a year ago

I still suggest you try out jQuery - it removes all the nasty browser dependency (for the most part) like having to do object detection for the XMLHttpRequest.

Jonathan Fingland · Accepted Answer · 2009-10-20 13:51:09Z

0

The method for evaluating your Xpath is not correct for firefox.

See https://developer.mozilla.org/en/Introduction_to_using_XPath_in_JavaScript For a good intro to using XPath in firefox.

Also see http://www.w3.org/TR/xpath for XPath details

For your example, you would need

var node = xmlDoc.evaluate("/bookstore/appSettings/add[@key='myKey']", xmlDoc, null,XPathResult.FIRST_ORDERED_NODE_TYPE,null).singleNodeValue;

See http://www.w3schools.com/XPath/xpath_examples.asp for How to accomplish this in both IE and firefox

edited Oct 20, 2009 at 13:51

answered Oct 20, 2009 at 13:46

Jonathan Fingland

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2 Comments

Rubens Farias Over a year ago

where do you need xmlDoc.evaluate?

Jonathan Fingland Over a year ago

document.evaluate() is for DOM3 XPath supporting browsers

Rubens Farias · Accepted Answer · 2009-10-20 14:05:07Z

0

Just to make sure your XML is returning correctly, can you please alter your code:

// ...
xhttp.send("");
xmlDoc=xhttp.responseXML;

alert(xmlDoc.xml)

I suspect you don't get your XML data back from your request.

answered Oct 20, 2009 at 14:05

Rubens Farias

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Comments

fglez · Accepted Answer · 2009-10-21 08:10:37Z

0

Before dealing with JavaScript, I would try to open the XML document directly in the browser typing the URL and see if it displays correctly.

answered Oct 21, 2009 at 8:10

fglez

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