Phone number input formatting and validation in Webflow

<script src="https://cdn.jsdelivr.net/npm/libphonenumber-js@1/bundle/libphonenumber-min.js"></script>
<script>
  const DEFAULT_COUNTRY = "US";
  const formatter = new libphonenumber.AsYouType(DEFAULT_COUNTRY);
  const phoneInput = document.getElementById("application-form-phone");
  phoneInput.addEventListener("input", function (event) {
    formatter.reset();
    const newValue = formatter.input(phoneInput.value);
    phoneInput.value = newValue;
    if (!libphonenumber.isValidPhoneNumber(newValue, DEFAULT_COUNTRY)) {
      phoneInput.setCustomValidity("Invalid phone number");
    } else {
      phoneInput.setCustomValidity("");
    }
  });
</script>