Regular Expressions 101

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/
(["'])((?:\\\1|(?!\1).)+)\1
/
g
1st Capturing Group
(["'])
Match a single character present in the list below
["']
"'
matches a single character in the list "' (case sensitive)
2nd Capturing Group
((?:\\\1|(?!\1).)+)
Non-capturing group
(?:\\\1|(?!\1).)+
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
1st Alternative
\\\1
\\ matches the character \ with index 9210 (5C16 or 1348) literally (case sensitive)
\1 matches the same text as most recently matched by the 1st capturing group
2nd Alternative
(?!\1).
Negative Lookahead
(?!\1)
Assert that the Regex below does not match
\1 matches the same text as most recently matched by the 1st capturing group
. matches any character (except for line terminators)
\1 matches the same text as most recently matched by the 1st capturing group
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