NAMESPACEERR

NAMESPACEERR is an error name used in the context of the Document Object Model (DOM) and XML processing to indicate an invalid namespace operation. It is the variant spelling of the standard NAMESPACE_ERR.

Origin and usage: In the DOM Level 2 specification, the error is defined as NAMESPACE_ERR with a numeric code (historically 14), representing attempts to perform namespace-related operations that are not allowed. Some language bindings or older documentation spell it without the underscore as NAMESPACEERR. It is part of the DOMException family and can be thrown by operations such as createElementNS, setAttributeNS, or importNode when the operation would violate namespace constraints.

Causes: Examples include using a prefixed name in createElement with a prefix that is not bound to a namespace, attempting to move a node from one document to another when the namespaces do not align, or creating or modifying attributes with misused prefixes.

Modern status: Today, DOM exceptions use the name property NamespaceError in most web APIs, with a numeric code being a legacy detail. Bindings may expose NAMESPACE_ERR constant in JavaScript as DOMException.NAMESPACE_ERR, while some code may refer to NAMESPACEERR without the underscore. The term remains primarily historical or bibliographic rather than an active API name.