Regex Flags Reference (i, g, m, s, u, y, x)

Regex flags (modifiers) change how a pattern matches — case, multi-line, dot-matches-newline, sticky, unicode. The set of supported flags differs between languages and so does their behavior. This reference lists every flag, what it does, and which languages support it.

How to use the Regex Flags Reference (i, g, m, s, u, y, x)

Browse or filter by keyword. Each flag card shows: letter, name, description, language support matrix (JavaScript / Python / Perl / PCRE), and an example before/after.