Regular Expressions 101

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/
[^\W_](?:[\s\S][^\W_])?
/
gm
Match a single character not present in the list below
[^\W_]
\W matches any non-word character (equivalent to [^a-zA-Z0-9_])
_ matches the character _ literally (case sensitive)
Non-capturing group
(?:[\s\S][^\W_])?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[\s\S]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\s matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
\S matches any non-whitespace character (equivalent to [^\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
Match a single character not present in the list below
[^\W_]
\W matches any non-word character (equivalent to [^a-zA-Z0-9_])
_ matches the character _ literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
gm

Test String

Regular Expressions 101

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