Robust Shopify Cart JS Methods

shopifyCartMethods

  __init__: function (p) {
    var self = this;
    self.initialConfig = p;				
    Shopify.queue = [];
  },
  
  addItem: function(prod,num, attr) {
    var num = (num) ? num : 1;
    this.pushQueue(prod,num,attr);
  },
  
  removeItem: function(prod,attr) {
    this.pushQueue(prod,0,attr);
  },
  
  pushQueue: function(id,n,attr) {
    Shopify.queue.push( {
      variantId: id,
      quantity: n,
      attributes: attr
    } );
    
    this.moveAlong();
  },
  
  moveAlong: function() {
    // If we still have requests in the queue, let's process the next one.
    if (Shopify.queue.length) {
      var request = Shopify.queue.shift();
      if (request.attributes) {
        Shopify.updateCartAttributes(request.attributes,function(){})
    	}
      if (request.quantity > 0) {
        Shopify.addItem(request.variantId, request.quantity, this.moveAlong);
      } else {
        Shopify.removeItem(request.variantId, this.moveAlong);
      }
    }
    // If the queue is empty, we will redirect to the cart page.
    else {
      document.location.href = '/cart';
    }
  }

Usage:
VC.addItem({{id}},1,{'gift-box':true});
or
VC.removeItem({{id}},{'gift-box':''});