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var selectCallback = function(variant, selector) {
  if (variant && variant.available) {               
    if (variant.inventory_management != '' && variant.inventory_quantity < 0) {
      $('.backorder').show();
    }
    else {
      $('.backorder').hide();
    }
    $("input#add").removeClass("disabled").removeAttr("disabled");
    $("h2#price span").html(Shopify.formatMoney(variant.price, "{{ shop.money_format }}"));
    if (variant.compare_at_price) {
      $("h2#price del").html(Shopify.formatMoney(variant.compare_at_price, "{{ shop.money_format }}"));
    }
    else {
      $("h2#price del").empty();
    }
  } 
  else {
    $('.backorder').hide();
    $("input#add").addClass("disabled").attr("disabled", "disabled");
    var message = variant ? "Sold Out" : "Unavailable";
    $("h2#price span").text(message);
    $("h2#price del").empty();
  }
};