Linked options helper methods for Shopify. See this: http://docs.shopify.com/manual/configuration/store-customization/advanced-navigation/linked-product-options - Updated to work with sectioned themes (tested with District)

gistfile1.html

<script>
// (c) Copyright 2016 Caroline Schnapp. All Rights Reserved. Contact: mllegeorgesand@gmail.com
// See https://docs.shopify.com/themes/customization/navigation/link-product-options-in-menus
  
// Modified by Jonathan Moore (Style Hatch) https://github.com/jonathanmoore
/* 
	Updated to work with sectioned themes
    	- Added required methods from the deprecated options_selection.js
        - Triggers an initial variant change
        - Hides sold out variants with only one option
*/
window.addEventListener('DOMContentLoaded', function() {
  var Shopify = Shopify || {};
    
  // Required functionality from depricated options_selection.js
  Shopify.arrayIncludes = function(e, t) {
    for (var n = 0; n < e.length; n++)
        if (e[n] == t) return !0;
    return !1
  }, Shopify.uniq = function(e) {
      for (var t = [], n = 0; n < e.length; n++) Shopify.arrayIncludes(t, e[n]) || t.push(e[n]);
      return t
  }

  Shopify.optionsMap = {};

  Shopify.updateOptionsInSelector = function(selectorIndex) {
      
    switch (selectorIndex) {
      case 0:
        var key = 'root';
        var selector = jQuery('.single-option-selector:eq(0)');
        break;
      case 1:
        var key = jQuery('.single-option-selector:eq(0)').val();
        var selector = jQuery('.single-option-selector:eq(1)');
        break;
      case 2:
        var key = jQuery('.single-option-selector:eq(0)').val();  
        key += ' / ' + jQuery('.single-option-selector:eq(1)').val();
        var selector = jQuery('.single-option-selector:eq(2)');
    }
    
    var initialValue = selector.val();
    selector.empty();    
    var availableOptions = Shopify.optionsMap[key];
    for (var i=0; i<availableOptions.length; i++) {
      var option = availableOptions[i];
      var newOption = jQuery('<option></option>').val(option).html(option);
      selector.append(newOption);
    }
    jQuery('.swatch[data-option-index="' + selectorIndex + '"] .swatch-element').each(function() {
      if (jQuery.inArray($(this).attr('data-value'), availableOptions) !== -1) {
        $(this).removeClass('soldout').show().find(':radio').removeAttr('disabled','disabled').removeAttr('checked');
      }
      else {
        $(this).addClass('soldout').hide().find(':radio').removeAttr('checked').attr('disabled','disabled');
      }
    });
    if (jQuery.inArray(initialValue, availableOptions) !== -1) {
      selector.val(initialValue);
    }
    selector.trigger('change');
    
  };

  Shopify.linkOptionSelectors = function(product) {
    // Building our mapping object.
    for (var i=0; i<product.variants.length; i++) {
      var variant = product.variants[i];
      if (variant.available) {
        // Gathering values for the 1st drop-down.
        Shopify.optionsMap['root'] = Shopify.optionsMap['root'] || [];
        Shopify.optionsMap['root'].push(variant.option1);
        Shopify.optionsMap['root'] = Shopify.uniq(Shopify.optionsMap['root']);
        // Gathering values for the 2nd drop-down.
        if (product.options.length > 1) {
          var key = variant.option1;
          Shopify.optionsMap[key] = Shopify.optionsMap[key] || [];
          Shopify.optionsMap[key].push(variant.option2);
          Shopify.optionsMap[key] = Shopify.uniq(Shopify.optionsMap[key]);
        }
        // Gathering values for the 3rd drop-down.
        if (product.options.length === 3) {
          var key = variant.option1 + ' / ' + variant.option2;
          Shopify.optionsMap[key] = Shopify.optionsMap[key] || [];
          Shopify.optionsMap[key].push(variant.option3);
          Shopify.optionsMap[key] = Shopify.uniq(Shopify.optionsMap[key]);
        }
      }
    }
    // Update options right away.
    Shopify.updateOptionsInSelector(0);
    if (product.options.length > 1) Shopify.updateOptionsInSelector(1);
    if (product.options.length === 3) Shopify.updateOptionsInSelector(2);
    // When there is an update in the first dropdown.
    jQuery(".single-option-selector:eq(0)").change(function() {
      Shopify.updateOptionsInSelector(1);
      if (product.options.length === 3) Shopify.updateOptionsInSelector(2);
      return true;
    });
    // When there is an update in the second dropdown.
    jQuery(".single-option-selector:eq(1)").change(function() {
      if (product.options.length === 3) Shopify.updateOptionsInSelector(2);
      return true;
    });  
  };
   
  {% if product.available and product.options.size > 1 %}
    var $addToCartForm = $('form[action="/cart/add"]');
    if (window.MutationObserver && $addToCartForm.length) {
      if (typeof observer === 'object' && typeof observer.disconnect === 'function') {
        observer.disconnect();
      }
      var config = { childList: true, subtree: true };
      var observer = new MutationObserver(function() {      
        Shopify.linkOptionSelectors({{ product | json }});
        observer.disconnect();
      });  
      observer.observe($addToCartForm[0], config);
    }
  {% endif %}
    
  var selector = jQuery('.single-option-selector:eq(0)');
  selector.trigger('change'); 

  {% if product.options.size == 1 %}
    {% for variant in product.variants %}
      {% unless variant.available %}
        jQuery('.single-option-selector option').filter(function() { return jQuery(this).text().trim() === {{ variant.title | json }}; }).remove();
      {% endunless %}
    {% endfor %}
    jQuery('.single-option-selector').trigger('change');
  {% endif %}
});
</script>

Hello,
Thanks for the script.
For those of you who are having issues with the default variant not loading and requiring the user to select a variant before the script fires:
This is what worked for me on the Shopify Debut Theme.
Find the following code:
Shopify.linkOptionSelectors({{ product | json }});
It is located in the following if statement

{% if product.available and product.options.size > 1 %}
...
Shopify.linkOptionSelectors({{ product | json }});
...
{% endif %}

Simply move it directly outside of the if statement:

{% if product.available and product.options.size > 1 %}
...
// Line removed from here
...
{% endif %}

// Line added here
Shopify.linkOptionSelectors({{ product | json }});

Keep working on Debut ... Thanks

Hi William,

I tried this and it worked on Flex theme (out of the sandbox) with 2 variant dropdowns so far that:

• if you change the first variant dropdown, the second dropdown only has variant options that are available.

However if you select one of the 2. variant options the selected option is not the same as the one that is displayed afterwards. It just changes after you select it.

also it does not work with default value of the 1. variant selection. only if you change the first variant.

Can somebody help me please on that?

It seems such an easy task but became a nightmare for me here :/

Thanks!
Ramiz

Anyone here got this to work with Prestige theme with 7.X.X? I would love to get it to work since i need this badly ;)

@roarsweden This is pretty outdated at this point. With the big shifts with Online Store 2.0 and how themes are structured now I doubt this would work with any theme created or updated in the last two years.

@jonathanmoore any pointers as to a solution that WOULD work with current themes?