How it works
Matching
Type a pattern and toggle flags: g finds every match, i ignores case, m lets ^ and $ match at each line, s lets the dot match a newline, u turns on Unicode mode and y matches only at the exact position. The text is searched with the browser’s own RegExp engine, so the result is what JavaScript code would give you.
Matches are marked in the text and listed with their position and each capture group. Named groups written as (?<name>...) are returned as well, and a group that did not take part shows as unmatched.
Replacing
Type a replacement to preview the whole text after replacing. In it $1, $2 insert capture groups, $<name> a named group, $& the whole match and $$ a dollar sign, exactly as in String.replace.
Limits
Only the first 1,000 matches are collected, and the list shows the first 100. An empty match, such as from x*, is counted but not highlighted; the search moves on by one character so it cannot loop forever.
