Regex Tester
//gu
Flags
Regex Tester
common.info
Regular expressions are patterns used to match character combinations in strings. They provide powerful way to search, replace, and validate text.
regex tester onlinejavascript regexflags gimsuylive highlight
Examples and real-life use cases
- Build and test validation patterns for emails, IDs or URLs.
- Extract data from logs with capture groups.
- Experiment with flags (g i m s u y) and zero-length matches.
FAQ
- Which flavor is used?
- The JavaScript (ECMAScript) regex engine available in your browser.
- Why do I see infinite loops sometimes?
- The tool guards against zero-length matches by advancing lastIndex; still, design patterns carefully.