Story change product option: story theme modification of https://gist.github.com/drabbytux/a49215c6d0ba16c4d096a56212bbc4ce

change_product_option.js

$(document).ready(function() {
  thumbnails = $('.product__thumbs img[src*="/products/"]');
  if (thumbnails.length) {
    thumbnails.on('click', function() {
      var arrImage = $(this).attr('src').split('?')[0].split('.');
      var strExtention = arrImage.pop();
      var strRemaining = arrImage.pop()
      .replace(/_(pico|icon|thumb|small|compact|medium|large|grande|crop|center)/gi, '')
      .replace(/_[a-zA-Z0-9@]+$/,'');
      var strNewImage = arrImage.join('.')+"."+strRemaining+"."+strExtention;
      if (typeof variantImages[strNewImage] !== 'undefined') {
          productOptions.forEach(function (value, i) {
           optionValue = variantImages[strNewImage]['option-'+i];
           if (optionValue !== null && optionValue !== 'undefined' && $('#SingleOptionSelector-'+i+' option').filter(function() {     
             var text = $(this).text();
             if(theme !== null && theme.strings !== 'undefined' ){
                text = text.replace(" - "+theme.strings.unavailable, "").replace(" - "+theme.strings.soldOut, "")
             }
             return text.trim() === optionValue }).length) {
             $('#SingleOptionSelector-'+i).val(optionValue).trigger('change');
           }
        });
      }
    });
  }
});