Regular Expressions 101

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/
function (?<name>[a-zA-Z0-9]+)\s*(?<arguments>\([^()]*\)(?::\s*[^{}\s]*)?)\s*(?<body>\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\})(?:;)?
/
gm
function
matches the characters function literally (case sensitive)
Named Capture Group name
(?<name>[a-zA-Z0-9]+)
Match a single character present in the list below
[a-zA-Z0-9]
+ 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)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Named Capture Group arguments
(?<arguments>\([^()]*\)(?::\s*[^{}\s]*)?)
\( matches the character ( with index 4010 (2816 or 508) literally (case sensitive)
Match a single character not present in the list below
[^()]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
()
matches a single character in the list () (case sensitive)
\) matches the character ) with index 4110 (2916 or 518) literally (case sensitive)
Non-capturing group
(?::\s*[^{}\s]*)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character not present in the list below
[^{}\s]
* 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)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Named Capture Group body
(?<body>\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\})
\{ matches the character { with index 12310 (7B16 or 1738) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
Non-capturing group
(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\{ matches the character { with index 12310 (7B16 or 1738) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
Non-capturing group
(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\{ matches the character { with index 12310 (7B16 or 1738) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
Non-capturing group
(?:\{[^\r{}]*(?:\{[^\r{}]*(?:\{[^\r{}]*\}[^\r{}]*)*\}[^\r{}]*)*\}[^\r{}]*)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\{ matches the character { with index 12310 (7B16 or 1738) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
Non-capturing group
(?:\{[^\r{}]*(?:\{[^\r{}]*\}[^\r{}]*)*\}[^\r{}]*)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\{ matches the character { with index 12310 (7B16 or 1738) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
Non-capturing group
(?:\{[^\r{}]*\}[^\r{}]*)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\{ matches the character { with index 12310 (7B16 or 1738) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
\} matches the character } with index 12510 (7D16 or 1758) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
\} matches the character } with index 12510 (7D16 or 1758) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
\} matches the character } with index 12510 (7D16 or 1758) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
\} matches the character } with index 12510 (7D16 or 1758) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
\} matches the character } with index 12510 (7D16 or 1758) literally (case sensitive)
Match a single character not present in the list below
[^\r{}]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\r matches a carriage return (ASCII 13)
{}
matches a single character in the list {} (case sensitive)
\} matches the character } with index 12510 (7D16 or 1758) literally (case sensitive)
Non-capturing group
(?:;)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
; matches the character ; with index 5910 (3B16 or 738) literally (case sensitive)
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