Regex Tester & Validator

Matches range/threshold selector strings such as 'low-', '3-', '<', '<-', '->', or '>' optionally followed by digits at line end, plus the literals 'other' and 'low-high', a digit followed by 'high' (e.g. '3high'), or lines containing only digits (including empty lines). Case-insensitive with global and multiline flags, making it useful for validating filter inputs like '<5', '>10', 'low-high', or plain numeric values.