- isEmpty(element, flags): boolean
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Parameters
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element: Alternative | CapturingGroup | ClassRangesCharacterClass | UnicodeSetsCharacterClass | CharacterClassRange | ClassIntersection | ClassStringDisjunction | ClassSubtraction | ExpressionCharacterClass | Group | LookaheadAssertion | LookbehindAssertion | Quantifier | StringAlternative | Backreference | EdgeAssertion | WordBoundaryAssertion | Character | AnyCharacterSet | EscapeCharacterSet | CharacterUnicodePropertyCharacterSet | StringsUnicodePropertyCharacterSet | readonly Alternative[]
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Returns boolean
Returns whether all (but at least one of the) paths of the given element do neither consume characters nor assert characters.
If this function returns
true, then isZeroLength and isPotentiallyEmpty are guaranteed to returntrue.Backreferences
A backreferences will only be considered potentially empty, iff it is empty by the definition of isEmptyBackreference.
Relations
isEmpty(e) -> isZeroLength(e)isEmpty(e) -> isPotentiallyEmpty(e)