class DocumentFragment

Detailed Description

<code> DocumentFragment </code> is a "lightweight" or "minimal" <code> Document </code> object. It is very common to want to be able to extract a portion of a document's tree or to create a new fragment of a document. Imagine implementing a user command like cut or rearranging a document by moving fragments around. It is desirable to have an object which can hold such fragments and it is quite natural to use a Node for this purpose. While it is true that a <code> Document </code> object could fulfil this role, a <code> Document </code> object can potentially be a heavyweight object, depending on the underlying implementation. What is really needed for this is a very lightweight object. <code> DocumentFragment </code> is such an object.

Furthermore, various operations -- such as inserting nodes as children of another <code> Node </code> -- may take <code> DocumentFragment </code> objects as arguments; this results in all the child nodes of the <code> DocumentFragment </code> being moved to the child list of this node.

The children of a <code> DocumentFragment </code> node are zero or more nodes representing the tops of any sub-trees defining the structure of the document. <code> DocumentFragment </code> nodes do not need to be well-formed XML documents (although they do need to follow the rules imposed upon well-formed XML parsed entities, which can have multiple top nodes). For example, a <code> DocumentFragment </code> might have only one child and that child node could be a <code> Text </code> node. Such a structure model represents neither an HTML document nor a well-formed XML document.

When a <code> DocumentFragment </code> is inserted into a <code> Document </code> (or indeed any other <code> Node </code> that may take children) the children of the <code> DocumentFragment </code> and not the <code> DocumentFragment </code> itself are inserted into the <code> Node </code> . This makes the <code> DocumentFragment </code> very useful when the user wishes to create nodes that are siblings; the <code> DocumentFragment </code> acts as the parent of these nodes so that the user can use the standard methods from the <code> Node </code> interface, such as <code> insertBefore() </code> and <code> appendChild() </code> .