Shopify:Remove old attributes from the cart

gistfile1.js

function getCartData(callback) {
  Shopify.getCart(function(cart){ 
    callback(cart);
  });
}

function updateCartAttributes(data, callback) {
  var params = {
    type: 'POST',
    url: '/cart/update.js',
    data: data,
    dataType: 'json',
    success: function(cart) {
      if ((typeof callback) === 'function') {
        callback(cart);
      }
      else {
        Shopify.api.onCartUpdate(cart);
      }
    },
    error: function(XMLHttpRequest, textStatus) {
      Shopify.api.onError(XMLHttpRequest, textStatus);
    }
  }; 
  $.ajax(params);
}

// Removes cart attributes for items that have been removed from the cart 
function removeOldAttributes() {
  getCartData(function(cart){
    var attrs = cart.attributes,
        items = cart.items,
        itemsToRemove = {};

    for (attr in attrs) {
      if (attrs.hasOwnProperty(attr)) {
        if (attr.indexOf('Backordered') !== -1) {
          var attrTitle = attr.split("- ")[1],
              removeAttr = false;

          for (itm in items) {
            if (items.hasOwnProperty(itm)) {
              var title = items[itm].title;

              if (title.indexOf(attrTitle) === -1) {
                removeAttr = true;
                itemsToRemove["attributes[" + attr + "]"] = "";
              }

            }
          }

        }
      }
    }

    updateCartAttributes(itemsToRemove, function(cart){
      // Perform additional actions if needed. 
    });

  });
}

// removeOldAttributes();

hi Christopher :
first, thanks for the code !
second, how we can use Shopify object in checkout page ?