The XMLSerializer method serializeToString() constructs a string representing the specified DOM tree in XML form.

rootNode

The Node to use as the root of the DOM tree or subtree for which to construct an XML representation.

A string containing the XML representation of the specified DOM tree.

TypeError

Thrown if the specified rootNode is not a compatible node type. The root node must be either Node or Attr.

InvalidStateError DOMException

Thrown if the tree could not be successfully serialized, probably due to issues with the content's compatibility with XML serialization.

SyntaxError DOMException

Thrown if a serialization of HTML was requested but could not succeed due to the content not being well-formed.

The specified root node—and all of its descendants—must be compatible with the XML serialization algorithm. The root node itself must be either a Node or Attr object.

The following types are also permitted as descendants of the root node, in addition to Node and Attr:

• DocumentType
• Document
• DocumentFragment
• Element
• Comment
• Text
• ProcessingInstruction
• Attr

If any other type is encountered, a TypeError exception is thrown.

There are some things worth noting about the XML output by serializeToString():

• For XML serializations, Element and Attr nodes are always serialized with their namespaceURI intact. This may mean that a previously-specified prefix or default namespace may be dropped or altered.
• The resulting XML is compatible with the HTML parser.
• Elements in the HTML namespace that have no child nodes (thereby representing empty tags) are serialized with both begin and end tags ("<someelement></someelement>") instead of using the empty-element tag ("<someelement/>").

• Parsing and serializing XML
• Serializing to HTML: Element.innerHTML and Element.outerHTML
• Parsing HTML or XML to create a DOM tree: DOMParser