namespaceURI of a Node is empty string, the serialization will treat them as null, ignoring the prefix if any. DOMSerializer accepts any node type for serialization. For nodes of type Document or Entity, well-formed XML will be created when possible (well-formedness is guaranteed if the document or entity comes from a parse operation and is unchanged since it was created). The serialized output for these node types is either as a XML document or an External XML Entity, respectively, and is acceptable input for an XML parser. For all other types of nodes the serialized form is not specified, but should be something useful to a human for debugging or diagnostic purposes.
Within a Document, DocumentFragment, or Entity being serialized, Nodes are processed as follows
Document nodes are written, including the XML declaration (unless the parameter "xml-declaration" is set to false) and a DTD subset, if one exists in the DOM. Writing a Document node serializes the entire document. Entity nodes, when written directly by DOMSerializer.write, outputs the entity expansion but no namespace fixup is done. The resulting output will be valid as an external entity. EntityReference nodes are serialized as an entity reference of the form "&entityName;" in the output. Child nodes (the expansion) of the entity reference are ignored. true, CDATA sections are split, and the unrepresentable characters are serialized as numeric character references in ordinary content. The exact position and number of splits is not specified. If the parameter is set to false , unrepresentable characters in a CDATA section are reported as "invalid-data-in-cdata-section" errors. The error is not recoverable - there is no mechanism for supplying alternative characters and continuing with the serialization. DocumentFragment nodes are serialized by serializing the children of the document fragment in the order they appear in the document fragment. Note: The serialization of a Node does not always generate a well-formed XML document, i.e. a DOMParser might throw fatal errors when parsing the resulting serialization.
Within the character data of a document (outside of markup), any characters that cannot be represented directly are replaced with character references. Occurrences of '<' and '&' are replaced by the predefined entities < and &. The other predefined entities (>, ', and ") might not be used, except where needed (e.g. using > in cases such as ']]>'). Any characters that cannot be represented directly in the output character encoding are serialized as numeric character references.
To allow attribute values to contain both single and double quotes, the apostrophe or single-quote character (') may be represented as "'", and the double-quote character (") as """. New line characters and other characters that cannot be represented directly in attribute values in the output character encoding are serialized as a numeric character reference.
Within markup, but outside of attributes, any occurrence of a character that cannot be represented in the output character encoding is reported as an error. An example would be serializing the element <LaCa\u00f1ada/> with encoding="us-ascii".
When requested by setting the parameter " normalize-characters" on DOMSerializer to true, character normalization is performed according to the rules defined in [CharModel] on all data to be serialized, both markup and character data. The character normalization process affects only the data as it is being written; it does not alter the DOM's view of the document after serialization has completed.
When outputting unicode data, whether or not a byte order mark is serialized, or if the output is big-endian or little-endian, is implementation dependent.
Namespaces are fixed up during serialization, the serialization process will verify that namespace declarations, namespace prefixes and the namespace URI's associated with elements and attributes are consistent. If inconsistencies are found, the serialized form of the document will be altered to remove them. The method used for doing the namespace fixup while serializing a document is the algorithm defined in Appendix B.1, "Namespace normalization", of [DOM Level 3 Core] .
Any changes made affect only the namespace prefixes and declarations appearing in the serialized data. The DOM's view of the document is not altered by the serialization operation, and does not reflect any changes made to namespace declarations or prefixes in the serialized output. We may take back what we say in the above paragraph depending on feedback from implementors, but for now the belief is that the DOM's view of the document is not changed during serialization.
While serializing a document, the parameter "discard-default-content" controls whether or not non-specified data is serialized.
While serializing, errors are reported to the application through the error handler (DOMSerializer.config's " error-handler" parameter). This specification does in no way try to define all possible errors that can occur while serializing a DOM node, but some common error cases are defined. The types (DOMError.type) of errors and warnings defined by this specification are:
"invalid-data-in-cdata-section" [fatal]false and invalid data is encountered in a CDATA section. "unsupported-encoding" [fatal]"unbound-namespace-in-entity" [warning]true and an unbound namespace prefix is encounterd in a referenced entity. "no-output-specified" [fatal]DOMOutput if no output is specified in the DOMOutput. In addition to raising the defined errors and warnings, implementations are expected to raise implementation specific errors and warnings for any other error and warning cases such as IO errors (file not found, permission denied,...) and so on.
See also the Document Object Model (DOM) Level 3 Load and Save Specification.
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