Regular Expressions 101

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/
(\n|\s)(?:(?:\+?(\d{1}|\d{2}|\d{3})\s*)\s*(?:\(\s*(\d{1}|\d{2}|\d{3})\s*\)|(\d{1,3}))\s*\-?(?:\(\s*(\d{1,3})\s*\)|(\d{3}))\s*\-?(?:\d{2}\s*\-?\d{2}))
/
gm
1st Capturing Group
(\n|\s)
1st Alternative
\n
\n matches a line-feed (newline) character (ASCII 10)
2nd Alternative
\s
\s matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
Non-capturing group
(?:(?:\+?(\d{1}|\d{2}|\d{3})\s*)\s*(?:\(\s*(\d{1}|\d{2}|\d{3})\s*\)|(\d{1,3}))\s*\-?(?:\(\s*(\d{1,3})\s*\)|(\d{3}))\s*\-?(?:\d{2}\s*\-?\d{2}))
Non-capturing group
(?:\+?(\d{1}|\d{2}|\d{3})\s*)
\+
matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
2nd Capturing Group
(\d{1}|\d{2}|\d{3})
1st Alternative
\d{1}
\d
matches a digit (equivalent to [0-9])
{1} matches the previous token exactly one time (meaningless quantifier)
2nd Alternative
\d{2}
\d
matches a digit (equivalent to [0-9])
{2} matches the previous token exactly 2 times
3rd Alternative
\d{3}
\d
matches a digit (equivalent to [0-9])
{3} matches the previous token exactly 3 times
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Non-capturing group
(?:\(\s*(\d{1}|\d{2}|\d{3})\s*\)|(\d{1,3}))
1st Alternative
\(\s*(\d{1}|\d{2}|\d{3})\s*\)
\( matches the character ( with index 4010 (2816 or 508) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
3rd Capturing Group
(\d{1}|\d{2}|\d{3})
1st Alternative
\d{1}
\d
matches a digit (equivalent to [0-9])
{1} matches the previous token exactly one time (meaningless quantifier)
2nd Alternative
\d{2}
\d
matches a digit (equivalent to [0-9])
{2} matches the previous token exactly 2 times
3rd Alternative
\d{3}
\d
matches a digit (equivalent to [0-9])
{3} matches the previous token exactly 3 times
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\) matches the character ) with index 4110 (2916 or 518) literally (case sensitive)
2nd Alternative
(\d{1,3})
4th Capturing Group
(\d{1,3})
\d
matches a digit (equivalent to [0-9])
{1,3} matches the previous token between 1 and 3 times, as many times as possible, giving back as needed (greedy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\-
matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
Non-capturing group
(?:\(\s*(\d{1,3})\s*\)|(\d{3}))
1st Alternative
\(\s*(\d{1,3})\s*\)
\( matches the character ( with index 4010 (2816 or 508) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
5th Capturing Group
(\d{1,3})
\d
matches a digit (equivalent to [0-9])
{1,3} matches the previous token between 1 and 3 times, as many times as possible, giving back as needed (greedy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\) matches the character ) with index 4110 (2916 or 518) literally (case sensitive)
2nd Alternative
(\d{3})
6th Capturing Group
(\d{3})
\d
matches a digit (equivalent to [0-9])
{3} matches the previous token exactly 3 times
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\-
matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
Non-capturing group
(?:\d{2}\s*\-?\d{2})
\d
matches a digit (equivalent to [0-9])
{2} matches the previous token exactly 2 times
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\-
matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
\d
matches a digit (equivalent to [0-9])
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.

Regular Expression
No Match

/
/
gm

Test String