Regular Expressions 101

Group 1([!?])

Character Class[!?]

!the literal ! (33₁₀ / 41₈ / 21₁₆)

?the literal ? (63₁₀ / 77₈ / 3F₁₆)

.*any character (except for line terminators), repeated any number of times

\1the text saved by group 1

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

([!?]).*\1

New

const string1 = "!hello"; // should return false
const string2 = "!hello?"; // should return false
const string3 = "!hello!"; // should return true
const string4 = "hello ??"; // should return true
const string5 = "hello ?test? foo"; // should return true
const string6 = "hello ?test ?? foo"; // should return true

Regular Expression

Substitution