How the tester works
The pattern uses JavaScript regular-expression syntax. Common flags include g for all matches, i for case-insensitive matching, m for multiline anchors, and s to let a dot match newlines.
Capture groups
Parentheses capture portions of a match. The results show each complete match followed by its captured groups and zero-based position.
Runaway protection
Regular expressions execute in an isolated browser worker. Expressions that exceed the short execution limit are stopped rather than freezing the page.