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Retrieving XML

After you’ve gotten XML into a DOM, it’s logical to assume you must be able to get that XML back out.

Microsoft made this easy by adding an

xml

property for every node, including a document node, which

returns its representative XML code as a string. So to retrieve the XML that you just loaded is simple:

oXmlDom.load(“test.xml”);

alert(oXmlDom.xml);

You can also retrieve the XML for a particular node:

var oNode = oXmlDom.documentElements.childNodes[1];

alert(oNode.xml);

The

xml

property is read-only and causes an error if you try to assign a value to it.

Parsing errors

When you try to load XML into an XML DOM object, whether by using

loadXML()

load()

, there’s

the possibility that the XML isn’t well-formed. To provide for this, the Microsoft XML DOM has a prop-

erty called

parseError

that contains all the information about any errors encountered while parsing

XML code.

The

parseError

property is actually an object with the following properties:

errorCode

— Numeric code indicating the type of error that occurred (0 when there’s no error)

filePos

— Position within the file where the error occurred

line

— The line on which the error occurred

linepos

– The character on the line where the error occurred

reason

— A plain text explanation of the error

srcText

— The code that caused the error

url

— The URL of the file that caused the error (if available)

When the

parseError

property is used by itself, it returns the value of

errorCode

, meaning that you

can check for errors by doing this:

if (oXmlDom.parseError != 0) {

//there were errors, do something about it here

}

Always check that the error code is not equal to 0, rather than if it’s greater than or less than 0, because

error codes can be either positive or negative.

You can use the

parseError

object to create your own error dialogs:

if (oXmlDom.parseError != 0) {

var oError = oXmlDom.parseError;

alert(“An error occurred:\nError Code: “

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XML in JavaScript

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