attribute is specified

operator

Return type:
Switch
Returns:
Returns true when the attribute has a value, and false otherise. Replacing is with isnt reverses the result.
Syntax
attribute attribute-name (of element-expression)? (is | isnt) specified


Purpose

The is specified attribute type test succeeds when:

  • the referenced element attribute has a value specified in the start tag in the document instance or,
  • the referenced data attribute has a value specified in the external entity declaration of the DTD.

The test fails otherwise. Using isnt instead of is reverses the results.

Unlike all other attribute references, no error occurs if the specified attribute does not exist, or was not given a value, since the test does not actually use the value.

If the element-expression references an element that does not exist, or if the specified attribute is not declared, the is form of the test always fails, and the isnt form always succeeds.

Related Syntax
Related Concepts