DocumentFragmentis a "lightweight" or "minimal"
Documentobject. 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
Documentobject could fulfill this role, a
Documentobject can potentially be a heavyweight object, depending on the underlying implementation. What is really needed for this is a very lightweight object.
DocumentFragmentis such an object.
Furthermore, various operations -- such as inserting nodes as children of another
Node-- may take
DocumentFragmentobjects as arguments; this results in all the child nodes of the
DocumentFragmentbeing moved to the child list of this node.
The children of a
DocumentFragmentnode are zero or more nodes representing the tops of any sub-trees defining the structure of the document.
DocumentFragmentnodes 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
DocumentFragmentmight have only one child and that child node could be a
Textnode. Such a structure model represents neither an HTML document nor a well-formed XML document.
DocumentFragmentis inserted into a
Document(or indeed any other
Nodethat may take children) the children of the
DocumentFragmentand not the
DocumentFragmentitself are inserted into the
Node. This makes the
DocumentFragmentvery useful when the user wishes to create nodes that are siblings; the
DocumentFragmentacts as the parent of these nodes so that the user can use the standard methods from the
Nodeinterface, such as
See also the Document Object Model (DOM) Level 2 Core Specification.