javascript

Chapter 15: XML in JavaScript
To parse an XML string, you must first create a DOM document and then call the loadXML() method.
When the document is first created, it is completely empty and so cannot be interacted with. Passing an
XML string into loadXML() parses the XML into the DOM document. Here’s an example:
var xmldom = createDocument();
xmldom.loadXML(“ < root > < child/ > < /root > ”);
alert(xmldom.documentElement.tagName); //”root”
alert(xmldom.documentElement.firstChild.tagName); //”child”
var anotherChild = xmldom.createElement(“child”);
xmldom.documentElement.appendChild(anotherChild);
var children = xmldom.getElementsByTagName(“child”);
alert(children.length); //2
Once the DOM document is filled with XML content, it can be interacted with just like any other DOM
document, including all methods and properties.
Parsing errors are represented by the parseError property, which is an object with several properties
relating to any parsing issues. These properties are as follows:
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errorCode — Numeric code indicating the type of error that occurred or 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)
The valueOf() method for parseError returns the value of errorCode , so you can check to see if a
parsing error occurred by using the following:
if (xmldom.parseError != 0){
alert(“Parsing error occurred.”);
}
An error code maybe a positive or negative number, so you need only check to see if it ’ s not equal to 0.
The details of the parsing error are easily accessible and can be used to indicate more useful error
information, as shown in the following example:
if (xmldom.parseError != 0){
alert(“An error occurred:\nError Code: “
+ xmldom.parseError.errorCode + “\n”
+ “Line: “ + xmldom.parseError.line + “\n”
+ “Line Pos: “ + xmldom.parseError.linepos + “\n”
+ “Reason: “ + xmldom.parseError.reason);
}
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