selectsize.js

const selectSize = (size) => {
  const selector = document.querySelector('#exp-pdp-buying-tools-container > form > div.exp-pdp-size-and-quantity-container > div > div.exp-pdp-size-dropdown-container.nsg-form--drop-down--option-container.selectBox-options.nsg-form--drop-down.exp-pdp-size-dropdown.exp-pdp-dropdown.two-column-dropdown.selectBox-dropdown-menu > ul');
  const children = Array.from(selector.children);
  children.forEach(ele => {
    const rel = ele.getAttribute('rel');
    if (rel.substring(rel.indexOf(':'), rel.length) === `:${size}`) {
      console.log('find ele', ele);
      $('select[name="skuAndSize"]').val(rel);
      $('#buyingtools-add-to-cart-button').click();
    }
  });
}