How do I display this regex result in javascript? - regex

Question

Regular expressions aren't exactly my strong suit. I got a regex for validating international phone numbers here. The validation bit works for me but I don't understand how I can take the regex result and use it to format the number. My question is how do I figure out, from the regex, what the groupings are that I can use to display?
var intl1RegexObj = /^((\+)?[1-9]{1,2})?([-\s\.])?((\(\d{1,4}\))|\d{1,4})(([-\s\.])?[0-9]{1,12}){1,2}$/;
if (IntlRegexObj.test(businessPhoneValue))
{
var formattedPhoneNumber = businessPhoneValue.replace(IntlRegexObj, "($1)");
// display formatted result
}

Answer 1

After simplifying that mess of a regex:
if (subject.match(/^((?:\+)?[1-9]{1,2})?[\-\s.]?((?:\(\d{1,4}\))|\d{1,4})([\-\s.]?\d{1,12}){1,2}$/)) {
// Successful match
}
There are now only 3 capturing groups.
First one $1 is easy, the country code with an optional +.
Then you have the local area code, basically 1-4 numbers with / without parentheses optionally prefixed by [-\s.]. That's $2
Finally you have your the actual phone number which can be from 1 to 24 numbers, including optional space or dot or minus sign [-\s.]
More detailed explanation:
"
^ # Assert position at the beginning of the string
( # Match the regular expression below and capture its match into backreference number 1
(?: # Match the regular expression below
\+ # Match the character “+” literally
)? # Between zero and one times, as many times as possible, giving back as needed (greedy)
[1-9] # Match a single character in the range between “1” and “9”
{1,2} # Between one and 2 times, as many times as possible, giving back as needed (greedy)
)? # Between zero and one times, as many times as possible, giving back as needed (greedy)
[-\s.] # Match a single character present in the list below
# The character “-”
# A whitespace character (spaces, tabs, line breaks, etc.)
# The character “.”
? # Between zero and one times, as many times as possible, giving back as needed (greedy)
( # Match the regular expression below and capture its match into backreference number 2
# Match either the regular expression below (attempting the next alternative only if this one fails)
(?: # Match the regular expression below
\( # Match the character “(” literally
\d # Match a single digit 0..9
{1,4}# Between one and 4 times, as many times as possible, giving back as needed (greedy)
\) # Match the character “)” literally
)
| # Or match regular expression number 2 below (the entire group fails if this one fails to match)
\d # Match a single digit 0..9
{1,4} # Between one and 4 times, as many times as possible, giving back as needed (greedy)
)
( # Match the regular expression below and capture its match into backreference number 3
[-\s.] # Match a single character present in the list below
# The character “-”
# A whitespace character (spaces, tabs, line breaks, etc.)
# The character “.”
? # Between zero and one times, as many times as possible, giving back as needed (greedy)
\d # Match a single digit 0..9
{1,12} # Between one and 12 times, as many times as possible, giving back as needed (greedy)
){1,2} # Between one and 2 times, as many times as possible, giving back as needed (greedy)
$ # Assert position at the end of the string (or before the line break at the end of the string, if any)
"

Answer 2

This regex is whoefully inadequate. As I go to your link, even a couple of the ones listed in non-match will match with this regex. The regex is purely an overlap of possibilities by the look of the groupings that happen to be capture groupings. And any sense of parsing out real parts of the number are sadly destroyed with this regex.
Expanded, it looks like this:
^
(
(\+)?
[1-9]{1,2}
)?
([-\s\.])?
(
(
\(\d{1,4}\)
)
|
\d{1,4}
)
(
([-\s\.])?
[0-9]{1,12}
){1,2}
$
I even tried to forumulate a proper capture grouping for its parts and sadly it shows the problems.
^
(?: \+ )?
( [1-9]{1,2} |) # Capt Group 1, international code (or not)
(?| # Branch Reset
\( (\d{1,4}) \) # Capure Group 2, area code
| (\d{1,4})
)
(?:[-\s.])?
( # Capt Group 3, the rest ########-########
[0-9]{1,12}
[-\s.]?
[0-9]{1,12}?
)
$
There might be something better out there, but this is just a validation wonder that doesen't really work correctly for the most part to do even that.

Answer 3

Regular expressions are not used to format anything. They just tell you if the string you are validating abides by the regular expression's rules. Example would be in a form where a user is entering a phone number. If the string they enter into the form doesn't match the regular expression then the form's validation which uses the regular expression to check the string will say something like, "Phone number is not in correct format."