Regular Expressions 101

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/
(str)(?=(?:[^'"]|["'][^'"]*["'])*$)
/
g
1st Capturing Group
(str)
str
matches the characters str literally (case sensitive)
Positive Lookahead
(?=(?:[^'"]|["'][^'"]*["'])*$)
Assert that the Regex below matches
Non-capturing group
(?:[^'"]|["'][^'"]*["'])*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
1st Alternative
[^'"]
Match a single character not present in the list below
[^'"]
'"
matches a single character in the list '" (case sensitive)
2nd Alternative
["'][^'"]*["']
Match a single character present in the list below
["']
"'
matches a single character in the list "' (case sensitive)
Match a single character not present in the list below
[^'"]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
'"
matches a single character in the list '" (case sensitive)
Match a single character present in the list below
["']
"'
matches a single character in the list "' (case sensitive)
$ asserts position at the end of the string
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
g

Test String

Substitution

Processing...