FLEX3笔记！

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When an XML method is invoked on an XMLList with only one XML
instance, the method invocation is automatically forwarded to that XML instance. By
forwarding the method invocation, E4X lets the programmer treat an XMLList with
only one XML instance as though it were that instance.

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if we simply want to access the content of a text node as a String, not an
XML instance, we can use the XML class’s instance method toString( ) on its parent element.

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For text nodes that are interspersed with other elements, we can use the XML class’s
instance method text( ) to retrieve the text nodes not contained by elements
The text( ) method can also be used to retrieve the text nodes from an entire
XMLList, not just a single XML element

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When used on an XMLList instance, the parent( ) method returns null unless all
items in the list have the same parent, in which case that parent is returned

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Invoking parent( ) on an XMLList with a single XML instance is identical to invoking
parent( ) on that instance itself.

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When parent( ) is invoked on an XML instance that represents an attribute, it returns
the element on which the attribute is defined.

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That said, XML instances representing attributes never have children, and, hence,
have no need for the majority of the XML class’s methods. Instead, an XML instance
representing an attribute is used nearly exclusively for the simple attribute value it
represents. To access the value of an attribute, we use the XML class’s instance
method toString( ).

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When working with attributes, remember that an attribute’s value is always type
String, even if it contains what appears to be another type of data.To be used as a
datatype other than String, that value must be converted either explicitly or implicitly.

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parentNode.childNodeName is equivalent to parentNode.child(childNodeName) and
always refers to an XMLList instance, not an XML instance.

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When an XMLList instance has one XML instance only, XML methods can be
invoked on it; the XMLList instance automatically forwards the invocations to
the XML instance.