javascript

Chapter 16: ECMA Script for XML
You can also use the child() method to access an attribute by passing in the name of the attribute
prefixed with @ as shown here:
alert(employees.employee[0].child(“@position”));
//”Software Engineer”
Since any XML object property name can be used with child() , the @ character is necessary to
distinguish between tag names and attribute names.
It ’ s possible to access only attributes by using the attribute() method and passing in the name of the
attribute. Unlike child() , there is no need to prefix the attribute name with an @ character. Here’s an
example:
alert(employees.employee[0].attribute(“position”));
//”Software Engineer”
These three ways of accessing properties are available on both XML and XMLList types. When used on an
XML object, an XML object representing the attribute is returned; when used on an XMLList object, an
XMLList is returned containing attribute XML objects for all elements in the list. In the previous example,
for instance, employees.employee.@position will return an XMLList containing two objects — one
for the position attribute on the first < employee/ > element and one for the second.
To retrieve all attributes in an XML or XMLList object, you can use the attributes() method. This
method returns an XMLList of objects representing all attributes. This is the same as using the @*
pattern, as illustrated in this example:
//both lines get all attributes
var atts1 = employees.employee[0].@*;
var atts2 = employees.employee[0].attributes();
Changing attribute values in E4X is as simple as changing a property value. Simply assign a new value
to the property like this:
employees.employee[0].@position = “Author”;
//change position attribute
The change is then reflected internally, so when you serialize the XML object, the attribute value is
updated. This same technique can be used to add new attributes, as shown in the following example:
employees.employee[0].@experience = “8 years”;
employees.employee[0].@manager = “Jim Smith”;
//add experience attribute
//add manager attribute
Since attributes act like any other ECMAScript properties, you can also remove attributes by using the
delete operator as follows:
delete employees.employee[0].@position;
//delete position attribute
Property access for attributes allows for very simple interaction with the underlying XML structure.
554