Regular Expressions 101

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/
(([a-zá-ú]+)[\.,]?\s[A--Úa-zá-ú]){3,}\1
/
gm
1st Capturing Group
(([a-zá-ú]+)[\.,]?\s[A--Úa-zá-ú]){3,}
{3,} matches the previous token between 3 and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
2nd Capturing Group
([a-zá-ú]+)
Match a single character present in the list below
[a-zá-ú]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
à matches the character à with index 19510 (C316 or 3038) literally (case sensitive)
¡-à matches a single character in the range between ¡ (index 161) and à (index 195) (case sensitive)
º matches the character º with index 18610 (BA16 or 2728) literally (case sensitive)
Match a single character present in the list below
[\.,]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
, matches the character , with index 4410 (2C16 or 548) literally (case sensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
Match a single character present in the list below
[A--Úa-zá-ú]
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
à matches the character à with index 19510 (C316 or 3038) literally (case sensitive)
 matches a single character in the range between  (index 129) and à (index 195) (case sensitive)
š matches the character š with index 35310 (16116 or 5418) literally (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
à matches the character à with index 19510 (C316 or 3038) literally (case sensitive)
¡-à matches a single character in the range between ¡ (index 161) and à (index 195) (case sensitive)
º matches the character º with index 18610 (BA16 or 2728) literally (case sensitive)
\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)
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.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String

Substitution

Processing...