Lookarounds in Go: Why RE2 Says No, and What to Do Instead
Go's RE2 engine rejects lookaheads and lookbehinds outright — why, and three workaround strategies that don't need them.
Backreferences in Go: Why `\1` Doesn't Compile, and What to Do Instead
Go's regexp package can't compile \1-style backreferences — here's the RE2 reason and the capture-and-verify fix.
Named Backreferences in Go: `\k<name>` Won't Compile — Here's the Fix
Go supports named capture groups but not \k<name> or (?P=name) references — the same RE2 limit, with a named-capture fix.
Python's `(?P<name>...)` in JavaScript: Fixing "Invalid group"
JavaScript rejects Python's (?P<name>...) named groups with "Invalid group" — the one-character fix, plus the full conversion checklist.
Python's `(?P=name)` in JavaScript: Use `\k<name>` Instead
Python's (?P=name) backreference syntax throws "Invalid group" in JS — swap in \k<name>, plus the replacement-string gotchas.
Unicode Property Escapes (`\p{L}`) in Python: Why `re` Says No
Python's re module has never supported \p{L} Unicode property escapes — four ways around it, from the regex package to stdlib-only rewrites.
Test the workaround live
Every guide links to patterns you can run across JS, Python, and Go side by side in RegexPro's tester.
Open Regex Tester