Regular Expressions 101

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/
((\\)(?:\w[rR]ef\*))(\{.\})
/
g
1st Capturing Group
((\\)(?:\w[rR]ef\*))
2nd Capturing Group
(\\)
\\ matches the character \ literally (case sensitive)
Non-capturing group
(?:\w[rR]ef\*)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[rR]
rR matches a single character in the list rR (case sensitive)
ef matches the characters ef literally (case sensitive)
\*
matches the character * literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
3rd Capturing Group
(\{.\})
\{ matches the character { literally (case sensitive)
.
matches any character (except for line terminators)
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
\} matches the character } literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
g

Test String