How to replace entire string with Regex capture groups in JavaScript?

Question

In a NodeJS application, I have a phone number field in my data that displays any number of phone numbers, one after another, in the same string:

\n\n \n (555) 555-5555 (Main)\n\n, \n\n \n (777) 777-777 (Domestic Fax)\n\n

I want to extract only the 'Main' phone number and convert it to the format 555-555-5555, that is whatever the Main number is. Basically I just want to extract whatever number precedes 'Main' and make it more legible (replacing the space with the '-')

I got as far as finding the correct regex string

const phoneRegex = /^[ \\n]*$([0-9]{3})$( )([0-9]{3}-[0-9]{4}) $Main$.*$/

but when I try to replace the string, it doesn't work

foo.phone =foo.phone.replace(phoneRegex,'$1-$3')

I keep getting the entire matched portion -- that is all the \n's and everything up to and including '(Main)'

I have searched for how to replace the entire string with the capture groups, but I haven't figured it out.

Look beyond replace – you can extract a match first (see RegExp#exec or String#match), then create a new string from that. — Ry-
– Ry- ♦, Commented May 21, 2020 at 9:57
Try s.replace(/^\s*$(\d{3})$\s*(\d+)-(\d+)[^]*$/, '$1-$2-$3'), I believe the \n are the newline chars in your sample string (you must have copied/pasted the string literal value from the console rather than shared the literal text). — Wiktor Stribiżew
– Wiktor Stribiżew, Commented May 21, 2020 at 9:57
@WiktorStribiżew -- The \n characters actually come in the data returned -- I'm not sure how that would change the regex you provided — Cerulean
– Cerulean, Commented May 21, 2020 at 10:01
@WiktorStribiżew -- I'm afraid that didn't work. I keep getting the entire matched portion -- that is all the \n's and everything up to and including '(Main)' — Cerulean
– Cerulean, Commented May 21, 2020 at 10:07

Wiktor Stribiżew · Accepted Answer · 2020-05-21 10:07:53Z

1

You may use

var s = "\\n\\n  \\n  (555) 555-5555 (Main)\\n\\n, \\n\\n  \\n  (777) 777-777 (Domestic Fax)\\n\\n";
console.log(
  s.replace(/^[^]*?\((\d{3})\)\s*(\d+)-(\d+)\s*\(Main\)[^]*/, '$1-$2-$3')
);

Details

^ - start of string
[^]*? - any 0 or more chars, as few as possible
\( - a (
(\d{3}) - Group 1: three digits
\) - a ) char
\s* - 0+ whitespaces
(\d+) - Group 2: one or more digits
- - a hyphen
(\d+) - Group 3: one or more digits
\s* - 0+ whitespaces
$Main$ - a (Main) string
[^]* - the rest of the string.

See the regex demo.

answered May 21, 2020 at 10:07

Wiktor Stribiżew

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2 Comments

Cerulean Over a year ago

Perfect! Indeed, I was using Regex101.com to build my original string. It was cruder and less efficient than yours, but it seemed to match. I wonder why it wasn't replacing the entire matched string correctly. In any case, I'll review your answer.

Wiktor Stribiżew Over a year ago

@Cerulean I still think your string contains newlines and not \ + n char combinations, and your \ns are actually "\n"s. . does not match newlines and carriage returns.

Yevhen Horbunkov · Accepted Answer · 2020-05-21 10:07:33Z

1

Would that work for you?

const str = `\n\n  \n  (555) 555-5555 (Main)\n\n, \n\n  \n  (777) 777-777 (Domestic Fax)\n\n`,

      [,code, phone] = str.match(/\((\d{3})\)\s(\d{3}\-\d{4})\s\(Main\)/),
      result = `${code}-${phone}`
      
console.log(result)

edited May 21, 2020 at 10:07

answered May 21, 2020 at 9:59

Yevhen Horbunkov

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2 Comments

Cerulean Over a year ago

My bad -- I didn't want the 714 in the final result. (The 714 is from the actual data -- I was trying to make it more general with '555'). Basically I just want to extract whatever number precedes 'Main' and make it more legible (replacing the space with the '-')

Yevhen Horbunkov Over a year ago

@Cerulean : like that one?

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