format phone number

formatPhone.ts

static formatPhone(phone: string): string {
    var regexPhone = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;
    var regexExtension = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})[-. ]?[A-Za-z:. ]*([0-9]+)$/;

    if (regexExtension.test(phone)) {
        return phone.replace(regexExtension, "($1) $2-$3 x$4");
    } else if (regexPhone.test(phone)) {
        return phone.replace(regexPhone, "($1) $2-$3");
    } else {
        return phone;
    }
}