Javascript form validation

validation.js

<script>
  document.addEventListener("DOMContentLoaded", function () {
    var formSelector = 'form';
    document.querySelector(formSelector).addEventListener("submit", function (e) {
      var isValid = true;

      // Match all fields that have aria-required="true"
      var requiredFields = document.querySelectorAll("[aria-required='true']")

      // Loop over all required fields
      requiredFields.forEach(function (field) {
        var value = field.value;
        // Reset the style on the field
        field.style.border = undefined;

        // Check if value of the field is empty
        if (value === "") {
          isValid = false;
          // Add a red border to the field that's required
          field.style.border = "1px solid red";
        }
      })

      // Prevent the form from being submitted if not valid
      if (!isValid) {
        e.preventDefault();
      }
    });
  });
</script>