Regex Tester

JavaScript flavor

This tester uses your browser's JavaScript regular expression engine, so results match what RegExp does in JavaScript and Node.js. Other languages (PCRE, Python, Java) differ in details such as lookbehind support and named group syntax.

Flags

• g is always on here, so every match is listed.
• i ignores case, m makes ^ and $ match at line breaks, s lets . match newlines, u enables full Unicode matching.

Reading the results

Matches are highlighted in the text and listed with their position. Numbered capture groups and named groups ((?<name>...)) are shown for each match. An invalid pattern shows the engine's error message.

Performance warning

Patterns with nested quantifiers can run for a very long time on some inputs (catastrophic backtracking) and may freeze the tab. Test risky patterns on short text.