Error parsing XML file in JavaScript_问答_开发者

开发者 https://www.devze.com 2022-12-09 03:14 出处：网络

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.

相关专题：javascript xml

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;
    aler开发者_如何学JAVAt(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.

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.

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

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.

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.

Error parsing XML file in JavaScript

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