Telephone Number Validator balanced parenthesis

JavaScript
1

Tell us what’s happening:

I’m almost done with this exercise but I’m not able to figure out how to check for a balanced parenthesis.

Your code so far



function telephoneCheck(str) {
        var s = /^[1]?\s?\(?\d{3}[-.]?\)?\s?\d{3}[-']?\s?\d{4}$/;
        var a = s.test(str);
        return a;
    }

telephoneCheck(555-555-5555);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/telephone-number-validator/

2

Look into using the or operator along with groups

Regular_Expressions#special-or

3

Is better to do with HTML pattern="" 0-9 and there only can write numbers in a input element.