fn.prefixFromQName

fn.prefixfromqnamefnprefixfromqname

/apidoc/8.0/fn:prefix-from-QName.xml

Returns an xs:NCName representing the prefix of $arg. The empty sequence is returned if $arg is the empty sequence or if the value of $arg contains no prefix.

A qualified name.

arg

xs.QName?

xs.NCName?

fn.prefixFromQName(
   fn.QName("http://www.example.com/example", "person") )

=> empty sequence, because the QName constructed
   by fn.QName does not have a prefix

var foo = xdmp.unquote('<foo xml:lang="en"/>');
var node = foo.toArray()[0].xpath("./foo/@xml:lang");
fn.prefixFromQName(fn.nodeName(node));

=> xml