Shopify Swatches w/out selectCallback function

swatch.liquid

{% comment %}
  Set the extension of your color files below. Use 'png', 'jpeg', 'jpg' or 'gif'.
{% endcomment %}

{% assign file_extension = 'png' %}

{% if swatch == blank %}
  <div class="swatch error">
    <p>You must include the snippet swatch.liquid with the name of a product option.</p>
    <p>Use: <code>{% raw %}{% include 'swatch' with 'name of your product option here' %}{% endraw %}</code></p>
    <p>Example: <code>{% raw %}{% include 'swatch' with 'Color' %}{% endraw %}</code></p>
  </div>
{% else %}

  {% assign found_option = false %}
  {% assign is_color = false %}
  {% assign option_index = 0 %}

  {% for option in product.options %}
    {% if option == swatch %}
      {% assign found_option = true %}
      {% assign option_index = forloop.index0 %}
      <style>
        label[for="product-select-option-{{ option_index }}"] { display: none; }
        #product-select-option-{{ option_index }} { display: none; }
        #product-select-option-{{ option_index }} + .custom-style-select-box { display: none !important; }
      </style>
      <script>$(window).on('load',function() { $('.selector-wrapper:eq({{ option_index }})').hide(); });</script>
      {% assign downcased_option = swatch | downcase %}
      {% if downcased_option contains 'color' or downcased_option contains 'colour' %}
        {% assign is_color = true %}
      {% endif %}
    {% endif %}
  {% endfor %}

  <script>
    var handleSwatchClick = function(optionIndex, variant, selectorId) {
      if (variant) {
        var form = jQuery('#' + selectorId).closest('form');
        var swatchField = form.find('.swatch[data-option-index="' + optionIndex + '"]')
        var radioButtons = swatchField.find('input[type="radio"]')
        var idInput = document.querySelector('input[name="id"]')
        idInput.setAttribute('value', variant.id)

        for (let i = 0; i <= radioButtons.length; i++) {
          var button = $(radioButtons[i])
          if (button && button.length > 0) {
            button.attr("id") === selectorId ? button.attr('checked', 'checked') : button.removeAttr('checked')
          }
        }
      }
    }
  </script>

  {% unless found_option %}
    <div class="swatch error">
      <p>You included the snippet swatch.liquid with the name of a product option — <code>'{{ swatch }}'</code> — that does not belong to your product.</p>
      <p>Use <code>{% raw %}{% include 'swatch' with 'name of your product option here' %}{% endraw %}</code></p>
      <p>Example: <code>{% raw %}{% include 'swatch' with 'Color' %}{% endraw %}</code></p>
      <p><strong>This is case-sensitive!</strong> Do not put in <code>'color'</code> if your product option name is <code>'Color'</code>.</p>
    </div>
    {% else %}
    <div class="swatch clearfix" data-option-index="{{ option_index }}">
      <div class="header">{{ swatch }}{% if swatch == "Size" %} <span class="product-size-chart">[<a href="#">Measure Up</a>]</span>{% endif %}</div>
      <input
        name="id"
        value="{{ variant.id }}"
        type="hidden"
      >
      {% assign values = '' %}
      {% for variant in product.variants %}
        {% assign value = variant.options[option_index] %}
        {% unless values contains value %}
        {% assign values = values | join: ',' %}
        {% assign values = values | append: ',' | append: value %}
        {% assign values = values | split: ',' %}
        <div data-value="{{ value | escape }}" class="swatch-element {% if is_color %}color {% endif %}{{ value | handle }} {% if variant.available %}available{% else %}soldout{% endif %}">
          {% if is_color %}
            <div class="tooltip">{{ value }}</div>
          {% endif %}
          <input id="swatch-{{ option_index }}-{{ value | handle }}" type="radio" name="option-{{ option_index }}" value="{{ value | escape }}"{% if forloop.first %} checked="checked"{% endif %} {% unless variant.available %}disabled{% endunless %} onchange="handleSwatchClick({{ option_index }}, {{ variant | json | escape }}, 'swatch-{{ option_index }}-{{ value | handle }}')" />
          {% if is_color %}
            <label for="swatch-{{ option_index }}-{{ value | handle }}" class="{{ value | split: ' ' | last | handle }}" {% comment %}style="background-color: {{ value | split: ' ' | last | handle }}; background-image: url({{ value | handle | append: '.' | append: file_extension | asset_url }})"{% endcomment %}>
              <img class="crossed-out" src="{{ 'soldout.png' | asset_url }}" />
            </label>
          {% else %}
            <label for="swatch-{{ option_index }}-{{ value | handle }}">
              {{ value }}
              <img class="crossed-out" src="{{ 'soldout.png' | asset_url }}" />
            </label>
          {% endif %}
        </div>
        {% endunless %}
        {% if variant.available %}
        <script>
          jQuery('.swatch[data-option-index="{{ option_index }}"] .{{ value | handle }}').removeClass('soldout').addClass('available').find(':radio').removeAttr('disabled');
        </script>
        {% endif %}
      {% endfor %}
    </div>

  {% endunless %}

{% endif %}