Regular Expressions 101

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/
(?=.*\+[0-9]{3}\s?[0-9]{2}\s?[0-9]{3}\s?[0-9]{4,5}$)
/
gm
Positive Lookahead
(?=.*\+[0-9]{3}\s?[0-9]{2}\s?[0-9]{3}\s?[0-9]{4,5}$)
Assert that the Regex below matches
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
Match a single character present in the list below
[0-9]
{3} matches the previous token exactly 3 times
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 one times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[0-9]
{2} matches the previous token exactly 2 times
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 one times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[0-9]
{3} matches the previous token exactly 3 times
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 one times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[0-9]
{4,5} matches the previous token between 4 and 5 times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
$ asserts position at the end of a line
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