Name the pattern and flags
Only d g i m s u v y are accepted once each.
Three explicit steps
Enter, run, inspect
Run in a fresh worker
The UI remains outside the regex execution thread.
Inspect bounded evidence
Compare match values, captures and replacement output.
Developer text checks
Useful for extraction, validation prototypes and replacement drafts
- Inspect named date groups.
- Compare global and sticky matching.
- Try a Unicode property escape.
- Draft a native replacement string.
JavaScript RegExp · 250 ms limit
Test one expression without freezing the page
Run pattern, flags, text and replacement in a disposable worker with bounded matches.