Show script discount messages in checkout on your Shopify store

checkout-script-messages.liquid

(function() {
  // The events to listen for to append the messages
  // page:change is all we really need, but the page:load will fire sooner 
  // so the messages will be less likely to pop-in
  var events = ['page:load', 'page:change'];
  
  events.forEach(function(event) {
    document.addEventListener(event, appendScriptMessages);
  });
                            
  // The function that actually appends the messages
  function appendScriptMessages() {
    // Exit if discount messages are already shown
    if (document.querySelector('.script-discount-message')) { return; }
  
    var discountedItems = [
      {% for line_item in checkout.line_items %}
        {% if line_item.message != blank %}
        {
          id: {{ line_item.variant_id }},
          message: '{{ line_item.message }}'
        },
        {% endif %}
      {% endfor %}
    ];
    
    for(var i = 0; i < discountedItems.length; i++) {
      var productSelect = 'tr.product[data-variant-id="' + discountedItems[i].id + '"] .product__description';
      var message = document.createElement('span');
      message.className = 'script-discount-message';
      message.innerText = discountedItems[i].message;

      document.querySelector(productSelect).appendChild(message);
    }
  }
})();

Hey @srg-xx, this file is meant to be included in checkout.liquid as a snippet via {% include 'checkout-script-messages' %} near the closing </body> tag or you can just use the content directly in checkout.liquid