Type Alias ExistencePredicate

A function that checks whether a given title exists.

This function is returned by Mwbot.getExistencePredicate. It returns:

• true if the title is known to exist,
• false if the title is known to be missing,
• null if the existence of the title is unknown.

A null return value indicates one of the following:

• The title was not included in the original getExistencePredicate() input.
• The title is empty.
• The title is interwiki.
• The title is in the Special or Media namespaces.

The title parameter is automatically normalized; the caller does not need to normalize it manually.