패턴 입력하면 즉시 매칭 · 그룹 캡처 · 설명까지 — 서버 전송 없음
.Any character\dDigit [0-9]\wWord char [a-zA-Z0-9_]\sWhitespace^Start of string$End of string*0 or more+1 or more?0 or 1{n,m}n to m times(abc)Capture group(?:abc)Non-capture group[abc]Character set[^abc]Negated seta|bAlternation(?=a)Lookahead(?<=a)Lookbehind\bWord boundary