I don’t really have a code snippet, I just thought about it and tried this, but it didn’t work

const checkUserEmail = function (e) {
  const regex =
    /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:.[a-zA-Z0-9-]+)*$/;
  e.preventDefault();
  if (!regex.test(inputEmail.value)) {
    this.classList.toggle(".error");
  } else {
    return (inputEmail.value = "");
  }
};

form.addEventListener("submit", checkUserEmail, false);