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createNSResolver method (document, XMLDocument)

Browser support:

Creates an XPathNSResolver object from the specified node that can be used to get namespace URIs from namespace prefixes in the scope of the node.

When an XPath expression specified for the evaluate method contains namespaces, then an XPathNSResolver object also needs to be set for this method. For further details, see the page for the evaluate method.

Syntax:

object.createNSResolver (node);

You can find the related objects in the Supported by objects section below.

Parameters:

node

Required. A reference to the element that specifies the scope of the required namespaces.

Return value:

Returns the newly created XPathNSResolver object.

Example HTML code 1:

This example illustrates the use of the createNSResolver and evaluate methods:

Code

ajax.js

ns.xml

<head>
    <script type="text/javascript" src="ajax.js"></script>
    
    <script type="text/javascript">
        var httpRequest = null;
        
        function SendRequest () {
            if (!httpRequest) {
                httpRequest = CreateHTTPRequestObject ();   // defined in ajax.js
            }
            if (httpRequest) {          
                    // The requested file must be in the same domain that the page is served from.
                var url = "ns.xml";
                httpRequest.open ("GET", url, true);    // async
                httpRequest.onreadystatechange = OnStateChange;
                httpRequest.send (null);
            }
        }

        function OnStateChange () {
            if (httpRequest.readyState == 0 || httpRequest.readyState == 4) {
                if (IsRequestSuccessful (httpRequest)) {    // defined in ajax.js
                    GetParamTags ();
                }
                else {
                    alert ("Operation failed.");
                }
            }
        }

        function NSResolver (nsPrefix) {
            if (nsPrefix == "dotto") {
                return "http://help.dottoro.com/NS";
            }
            return null;
        }

        function GetParamTags () {
            var xmlDoc = ParseHTTPResponse (httpRequest);   // defined in ajax.js
            if (!xmlDoc)
                return;

            if (xmlDoc.createNSResolver) {
                var nsResolver = xmlDoc.createNSResolver (xmlDoc.documentElement);
                var params = xmlDoc.evaluate("//dotto:param", xmlDoc.documentElement, nsResolver, XPathResult.ANY_TYPE, null);
                var param = params.iterateNext();
                while (param) {
                    var paramName = param.getAttribute ("name");
                    var paramValue = param.getAttribute ("value");
                    alert ("<dotto:param name='" + paramName + "' value='" + paramValue + "' />");
                    param = params.iterateNext();
                }
            }
            else {
                alert ("Your browser doesn't support the createNSResolver method!");
            }
        }
    </script>
</head>
<body>
    <button onclick="SendRequest ()">Get param tags with 'dotto' namespaces</button>
</body>


function CreateHTTPRequestObject () {
        // although IE supports the XMLHttpRequest object, but it does not work on local files.
    var forceActiveX = (window.ActiveXObject && location.protocol === "file:");
    if (window.XMLHttpRequest && !forceActiveX) {
        return new XMLHttpRequest();
    }
    else {
        try {
            return new ActiveXObject("Microsoft.XMLHTTP");
        } catch(e) {}
    }
    alert ("Your browser doesn't support XML handling!");
    return null;
}

function CreateMSXMLDocumentObject () {
    if (typeof (ActiveXObject) != "undefined") {
        var progIDs = [
                        "Msxml2.DOMDocument.6.0", 
                        "Msxml2.DOMDocument.5.0", 
                        "Msxml2.DOMDocument.4.0", 
                        "Msxml2.DOMDocument.3.0", 
                        "MSXML2.DOMDocument", 
                        "MSXML.DOMDocument"
                      ];
        for (var i = 0; i < progIDs.length; i++) {
            try { 
                return new ActiveXObject(progIDs[i]); 
            } catch(e) {};
        }
    }
    return null;
}

function CreateXMLDocumentObject (rootName) {
    if (!rootName) {
        rootName = "";
    }
    var xmlDoc = CreateMSXMLDocumentObject ();
    if (xmlDoc) {
        if (rootName) {
            var rootNode = xmlDoc.createElement (rootName);
            xmlDoc.appendChild (rootNode);
        }
    }
    else {
        if (document.implementation.createDocument) {
            xmlDoc = document.implementation.createDocument ("", rootName, null);
        }
    }
    
    return xmlDoc;
}

function ParseHTTPResponse (httpRequest) {
    var xmlDoc = httpRequest.responseXML;

            // if responseXML is not valid, try to create the XML document from the responseText property
    if (!xmlDoc || !xmlDoc.documentElement) {
        if (window.DOMParser) {
            var parser = new DOMParser();
            try {
                xmlDoc = parser.parseFromString (httpRequest.responseText, "text/xml");
            } catch (e) {
                alert ("XML parsing error");
                return null;
            };
        }
        else {
            xmlDoc = CreateMSXMLDocumentObject ();
            if (!xmlDoc) {
                return null;
            }
            xmlDoc.loadXML (httpRequest.responseText);

        }
    }

            // if there was an error while parsing the XML document
    var errorMsg = null;
    if (xmlDoc.parseError && xmlDoc.parseError.errorCode != 0) {
        errorMsg = "XML Parsing Error: " + xmlDoc.parseError.reason
                  + " at line " + xmlDoc.parseError.line
                  + " at position " + xmlDoc.parseError.linepos;
    }
    else {
        if (xmlDoc.documentElement) {
            if (xmlDoc.documentElement.nodeName == "parsererror") {
                errorMsg = xmlDoc.documentElement.childNodes[0].nodeValue;
            }
        }
    }
    if (errorMsg) {
        alert (errorMsg);
        return null;
    }

        // ok, the XML document is valid
    return xmlDoc;
}

    // returns whether the HTTP request was successful
function IsRequestSuccessful (httpRequest) {
        // IE: sometimes 1223 instead of 204
    var success = (httpRequest.status == 0 || 
        (httpRequest.status >= 200 && httpRequest.status < 300) || 
        httpRequest.status == 304 || httpRequest.status == 1223);
    
    return success;
}

<?xml version="1.0" encoding="utf-8"?>
<ns xmlns="http://help.dottoro.com/defaultNS" xmlns:dotto="http://help.dottoro.com/NS">
    <item dotto:color="red">
        <dotto:title>Namespace example</dotto:title>
        <dotto:description>Describes how to use namespaces with tags and attributes.</dotto:description>
        <dotto:pubDate>Wed, 17 Aug 2009 13:58:41 +0200</dotto:pubDate>
        <dotto:link>http://help.dottoro.com</dotto:link>
    </item>
    <order>
        <dotto:param name="sortBy" value="title" />
        <dotto:param name="sortDir" value="ascending" />
    </order>
</ns>

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Example HTML code 2:

This example is equivalent to the previous one, but it implements a namespace resolver function for the evaluate method:

Code

ajax.js

ns.xml

<head>
    <script type="text/javascript" src="ajax.js"></script>
    
    <script type="text/javascript">
        var httpRequest = null;
        
        function SendRequest () {
            if (!httpRequest) {
                httpRequest = CreateHTTPRequestObject ();   // defined in ajax.js
            }
            if (httpRequest) {          
                    // The requested file must be in the same domain that the page is served from.
                var url = "ns.xml";
                httpRequest.open ("GET", url, true);    // async
                httpRequest.onreadystatechange = OnStateChange;
                httpRequest.send (null);
            }
        }

        function OnStateChange () {
            if (httpRequest.readyState == 0 || httpRequest.readyState == 4) {
                if (IsRequestSuccessful (httpRequest)) {    // defined in ajax.js
                    GetParamTags ();
                }
                else {
                    alert ("Operation failed.");
                }
            }
        }

        function NSResolver (nsPrefix) {
            if (nsPrefix == "dotto") {
                return "http://help.dottoro.com/NS";
            }
            return null;
        }

        function GetParamTags () {
            var xmlDoc = ParseHTTPResponse (httpRequest);   // defined in ajax.js
            if (!xmlDoc)
                return;

            if (xmlDoc.createNSResolver) {
                var params = xmlDoc.evaluate("//dotto:param", xmlDoc.documentElement, NSResolver, XPathResult.ANY_TYPE, null);
                var param = params.iterateNext();
                while (param) {
                    var paramName = param.getAttribute ("name");
                    var paramValue = param.getAttribute ("value");
                    alert ("<dotto:param name='" + paramName + "' value='" + paramValue + "' />");
                    param = params.iterateNext();
                }
            }
            else {
                alert ("Your browser doesn't support the createNSResolver method!");
            }
        }
    </script>
</head>
<body>
    <button onclick="SendRequest ()">Get param tags with 'dotto' namespaces</button>
</body>


function CreateHTTPRequestObject () {
        // although IE supports the XMLHttpRequest object, but it does not work on local files.
    var forceActiveX = (window.ActiveXObject && location.protocol === "file:");
    if (window.XMLHttpRequest && !forceActiveX) {
        return new XMLHttpRequest();
    }
    else {
        try {
            return new ActiveXObject("Microsoft.XMLHTTP");
        } catch(e) {}
    }
    alert ("Your browser doesn't support XML handling!");
    return null;
}

function CreateMSXMLDocumentObject () {
    if (typeof (ActiveXObject) != "undefined") {
        var progIDs = [
                        "Msxml2.DOMDocument.6.0", 
                        "Msxml2.DOMDocument.5.0", 
                        "Msxml2.DOMDocument.4.0", 
                        "Msxml2.DOMDocument.3.0", 
                        "MSXML2.DOMDocument", 
                        "MSXML.DOMDocument"
                      ];
        for (var i = 0; i < progIDs.length; i++) {
            try { 
                return new ActiveXObject(progIDs[i]); 
            } catch(e) {};
        }
    }
    return null;
}

function CreateXMLDocumentObject (rootName) {
    if (!rootName) {
        rootName = "";
    }
    var xmlDoc = CreateMSXMLDocumentObject ();
    if (xmlDoc) {
        if (rootName) {
            var rootNode = xmlDoc.createElement (rootName);
            xmlDoc.appendChild (rootNode);
        }
    }
    else {
        if (document.implementation.createDocument) {
            xmlDoc = document.implementation.createDocument ("", rootName, null);
        }
    }
    
    return xmlDoc;
}

function ParseHTTPResponse (httpRequest) {
    var xmlDoc = httpRequest.responseXML;

            // if responseXML is not valid, try to create the XML document from the responseText property
    if (!xmlDoc || !xmlDoc.documentElement) {
        if (window.DOMParser) {
            var parser = new DOMParser();
            try {
                xmlDoc = parser.parseFromString (httpRequest.responseText, "text/xml");
            } catch (e) {
                alert ("XML parsing error");
                return null;
            };
        }
        else {
            xmlDoc = CreateMSXMLDocumentObject ();
            if (!xmlDoc) {
                return null;
            }
            xmlDoc.loadXML (httpRequest.responseText);

        }
    }

            // if there was an error while parsing the XML document
    var errorMsg = null;
    if (xmlDoc.parseError && xmlDoc.parseError.errorCode != 0) {
        errorMsg = "XML Parsing Error: " + xmlDoc.parseError.reason
                  + " at line " + xmlDoc.parseError.line
                  + " at position " + xmlDoc.parseError.linepos;
    }
    else {
        if (xmlDoc.documentElement) {
            if (xmlDoc.documentElement.nodeName == "parsererror") {
                errorMsg = xmlDoc.documentElement.childNodes[0].nodeValue;
            }
        }
    }
    if (errorMsg) {
        alert (errorMsg);
        return null;
    }

        // ok, the XML document is valid
    return xmlDoc;
}

    // returns whether the HTTP request was successful
function IsRequestSuccessful (httpRequest) {
        // IE: sometimes 1223 instead of 204
    var success = (httpRequest.status == 0 || 
        (httpRequest.status >= 200 && httpRequest.status < 300) || 
        httpRequest.status == 304 || httpRequest.status == 1223);
    
    return success;
}

<?xml version="1.0" encoding="utf-8"?>
<ns xmlns="http://help.dottoro.com/defaultNS" xmlns:dotto="http://help.dottoro.com/NS">
    <item dotto:color="red">
        <dotto:title>Namespace example</dotto:title>
        <dotto:description>Describes how to use namespaces with tags and attributes.</dotto:description>
        <dotto:pubDate>Wed, 17 Aug 2009 13:58:41 +0200</dotto:pubDate>
        <dotto:link>http://help.dottoro.com</dotto:link>
    </item>
    <order>
        <dotto:param name="sortBy" value="title" />
        <dotto:param name="sortDir" value="ascending" />
    </order>
</ns>