Regular
Expressions
101
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Explanation
/
(
[^
rs
]
)(?=
\1
+
)
|
(
rr
)(?=
r
+
)
|
(
ss
)(?=
s
+
)
/
g
1st Alternative
(
[^
rs
]
)(?=
\1
+
)
1st Capturing Group
(
[^
rs
]
)
Match a single character not present in the list below
[^
rs
]
rs
matches a single character in the list
rs
(case sensitive)
Positive Lookahead
(?=
\1
+
)
Assert that the Regex below matches
\1
+
matches the same text as most recently matched by the
1st
capturing group
+
Quantifier
— Matches between
one
and
unlimited
times, as many times as possible, giving back as needed
(greedy)
2nd Alternative
(
rr
)(?=
r
+
)
2nd Capturing Group
(
rr
)
rr
matches the characters
rr
literally (case sensitive)
Positive Lookahead
(?=
r
+
)
Assert that the Regex below matches
r
+
matches the character
r
literally (case sensitive)
+
Quantifier
— Matches between
one
and
unlimited
times, as many times as possible, giving back as needed
(greedy)
3rd Alternative
(
ss
)(?=
s
+
)
3rd Capturing Group
(
ss
)
ss
matches the characters
ss
literally (case sensitive)
Positive Lookahead
(?=
s
+
)
Assert that the Regex below matches
s
+
matches the character
s
literally (case sensitive)
+
Quantifier
— Matches between
one
and
unlimited
times, as many times as possible, giving back as needed
(greedy)
Global pattern flags
g modifier:
g
lobal. All matches (don't return after first match)
Match Information
Your regular expression does not match the subject string.
Try launching the debugger to find out why.
Quick Reference
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Regular
Expressions
101
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