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Advanced Debuggers
Complex debugging scenarios.
20 Tools Available
Catastrophic Backtracking
WARNING: May freeze browser. Example: (x+x+)+y matches infinite x
/(x+x+)+y/
Nested Quantifiers
Debug nested loop behavior.
/(a*)*/
Zero-Width Match
Matches the start (zero width).
/^/
All Characters
Matches absolutely everything including newlines.
/[\s\S]*/
Greedy vs Lazy
Compare <tag>content</tag> matches.
/<.+> vs <.+?>/
Complex Email RFC
Full RFC 5322 validation pattern.
/(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])/
IPv6 Full Spec
Complex IPv6 validation.
/(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))/
HTML Parser (Fragile)
Naive HTML parser for debugging.
/<([A-Z][A-Z0-9]*)\b[^>]*>(.*?)</\1>/
Recursive Limit
Testing engine limits.
/a{1,1000}/
Unicode Ranges
Matches all BMP characters.
/[\u0000-\uFFFF]/
Invisible Control
Matches control characters (u flag).
/[\p{C}]/
Surrogate Pairs
Matches surrogate pairs explicitly.
/[�-�][�-�]/
Line Break Debug
Debugs newline formats.
/\r\n|\r|\n/
Tab vs Space
Debugs whitespace issues.
/\t|\s/
Empty Groups
Matches empty groups.
/()()()/
Word Edge Cases
Matches hyphenated or apostrophed words.
/\w+[-']\w+/
Anchor Conflicts
Matches empty string only.
/^$/
Lookbehind Chains
Chained lookbehinds.
/(?<=a)(?<=b)/
Emoji Sequences
Debugs emoji rendering (u flag).
/\p{Emoji_Presentation}/
Redundant Groups
Detects redundant capturing groups.
/((a))/