document.addEventListener('DOMContentLoaded', function () {
    function isIE() {
      const ua = window.navigator.userAgent;
      const msie = ua.indexOf('MSIE ');
      const trident = ua.indexOf('Trident/');

      return msie > 0 || trident > 0;
    }

    if (!isIE()) return;
    const cartSubmitInput = document.createElement('input');
    cartSubmitInput.setAttribute('name', 'checkout');
    cartSubmitInput.setAttribute('type', 'hidden');
    document.querySelector('#cart').appendChild(cartSubmitInput);
    document.querySelector('#checkout').addEventListener('click', function (event) {
      document.querySelector('#cart').submit();
    });
  });