JavaScript RegEx Format String Containing American Express Card Number

I'm trying to format a string containing an American Express credit card number using a regular expression. Here's what I'm using for Visa, MasterCard and Discover number formattin

Solution 1:

You can use:

var ccNum = '341256789012345';

var ccFmt = ccNum.replace(/\b(\d{4})(\d{6})(\d{5})\b/, '$1-$2-$3');
//=> 3412-567890-12345

RegEx Demo