Need help changing jquery to javascript for an on change function

I am trying to change some jQuery code to plain JS for an on call function. I keep getting the following error – Failed to execute ‘addEventListener’ on ‘EventTarget’: parameter 2 is not of type ‘Object’.

Old

$(document).on('change', '.js-variant-radio', onVariantRadioChange);

New

document.querySelector('.js-variant-radio').addEventListener("change", onVariantRadioChange);

Complete code block here

(function(){
  //START QUANTITY INPUT VALIDATION FUNCTION
  let
    onVariantRadioChange = function(event) {
      let
        $radio = document.querySelector(this),
        $form = $radio.closest('form'),
        max = $radio.attr('data-inventory-quantity'),
        $quantity = $form.querySelector('.js-quantity-field'),
        $addToCartButton = $form.querySelector('.add-to-cart-button');

      if($addToCartButton.prop('disabled') === true) {
        $addToCartButton.prop('disabled', false);
      }

      $quantity.attr('max', max);

      if (parseInt($quantity.value) > max) {
        $quantity.val(max).change();
      }
    };

    //END QUANTITY INPUT VALIDATION FUNCTION
})();

>Solution :

You’re still adding the event listener with jQuery. Try changing it to:

const jsVariantRadios = document.getElementsByClassName('.js-variant-radio');

jsVariantRadios.addEventListener('change', onVariantRadioChange);