From http://www.w3schools.com (Copyright Refsnes Data)

DTD Validation

With Internet Explorer 5+ you can validate your XML against a DTD.

Validating With the XML Parser

If you try to open an XML document, the XML Parser might generate an error. By accessing the parseError object, you can retrieve the error code, the error text, or even the line that caused the error.

Note: The load( ) method is used for files, while the loadXML( ) method is used for strings.

var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
xmlDoc.async="false";
xmlDoc.validateOnParse="true";
xmlDoc.load("note_dtd_error.xml");

document.write("<br />Error Code: ");
document.write(xmlDoc.parseError.errorCode);
document.write("<br />Error Reason: ");
document.write(xmlDoc.parseError.reason);
document.write("<br />Error Line: ");
document.write(xmlDoc.parseError.line);

Try it Yourself or just look at the XML file

Turning Validation Off

Validation can be turned off by setting the XML parser's validateOnParse="false".

var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
xmlDoc.async="false";
xmlDoc.validateOnParse="false";
xmlDoc.load("note_dtd_error.xml");

document.write("<br />Error Code: ");
document.write(xmlDoc.parseError.errorCode);
document.write("<br />Error Reason: ");
document.write(xmlDoc.parseError.reason);
document.write("<br />Error Line: ");
document.write(xmlDoc.parseError.line);

Try it Yourself

A General XML Validator

To help you check your xml files, you can syntax-check any XML file here.

The parseError Object

You can read more about the parseError object in our XML DOM tutorial.