Format phone number in Javascript

Question

I need to format phone number for example by replace():

From: +48 XX XXX XX XX where X is a number.

Example: +48 12 345 67 89

To: +48 XXX XXX XXX

Example: +48 123 456 789

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Edit:

My work:

• First, I tried to remove the spaces in string: phone.replace(' ', '');:

Before: +48 12 312 31 23

After: +4812 312 31 23

Conclusion: Something is wrong because it only formatted the first space instead of everything.

• I also tried to separate it into parts, based on other questions about regex:

phone.replace(/(\d{3})(\d{3})(\d{3})(\d{3})/gi, '$1 $2 $3 $4'); and

phone.replace(/(\d{3})" "(\d{3})" "(\d{3})" "(\d{3})/gi, '$1 $2 $3 $4');

and many other configurations like this.

Before: +48 12 312 31 23

After: +48 12 312 31 23

Conclusion: For sure, something is wrong, there is no change. The problem is with the regex.

Answer 1

FYI - string.replace() will only replace the first instance of whatever you want to replace whereas string.replaceAll() will replace all instances.

Answer 2

You could use a regex replacement approach here:

var input = "+48 12 345 67 89";
var output = input.replace(/\s+/g, "")
                  .replace(/^(\+\d{2})(\d{3})(\d{3})(\d{3})$/, "$1 $2 $3 $4");
console.log(input + " => " + output);