addItemWithAttachments.js

// Example input
var item = { id: 35, quantity: 3, seller: 1 }
var attachments = [
  {
    name: "Ingredientes Hamburguesa con Queso",
    values: [
      {
        "Sin Carne 50gr": "true",
        "Sin Cebolla": "false",
        "Sin Mostaza": "false",
        "Sin Pan Regular": "false",
        "Sin Pepinillos": "false",
        "Sin Queso Tajada": "false",
        "Sin Salsa de Tomate": "false"
      },
      {
        "Sin Carne 50gr": "false",
        "Sin Cebolla": "true",
        "Sin Mostaza": "false",
        "Sin Pan Regular": "false",
        "Sin Pepinillos": "false",
        "Sin Queso Tajada": "false",
        "Sin Salsa de Tomate": "false"
      },
      {
        "Sin Carne 50gr": "false",
        "Sin Cebolla": "false",
        "Sin Mostaza": "true",
        "Sin Pan Regular": "false",
        "Sin Pepinillos": "false",
        "Sin Queso Tajada": "false",
        "Sin Salsa de Tomate": "false"
      }
    ]
  },
  {
    name: "Open to Extras",
    values: [
      {
        "Open to Extras": "Extra Queijo"
      },
      {
        "Open to Extras": "Extra Bacon"
      },
      {
        "Open to Extras": "Extra Cebola"
      },
    ]
  }
]

//Implementation
function addItemWithAttachment(item, attachments) {
  var items = [item]

  return vtexjs.checkout.addToCart(items)
    .then((orderForm) => {

      // Find the recently added item index in the orderForm
      var indexToAddAttachment = orderForm.items.findIndex(function(orderItem) {
        return (
          orderItem.id.toString() === item.id.toString() &&
          orderItem.attachments.length === 0 &&
          orderItem.bundleItems.length === 0
        )
      })
      
      // Some error happened. The item was not added to the cart for some reason.
      if (indexToAddAttachment === -1) {
        return
      }

      var allRequests = attachments.reduce(function(acc, attachment, attachmentIndex) {
        var requests = attachment.values.map(function(attachmentValue, attachmentValueIndex) {
          return function(orderForm) {
            if (!attachmentValue) return $.Deferred().resolve(orderForm)

            if (attachmentIndex !== 0) {
              indexToAddAttachment = findItemIndexWithPreviousAttachments(
                orderForm.items, attachments, attachmentIndex, attachmentValueIndex
              )
              
              // Some error happened. The item was not added to the cart for some reason.
              if (indexToAddAttachment === -1) {
                return $.Deferred().resolve(orderForm)
              }
            }

            return vtexjs.checkout.addItemAttachment(
              indexToAddAttachment, attachment.name, attachmentValue, undefined, true
            )
          }
        })

        return acc.concat(requests)
      }, [])
      
      return serializeRequests(allRequests)
    })
}

function findItemIndexWithPreviousAttachments(
  items, attachments, attachmentIndex, attachmentValueIndex
) {
  return items.findIndex(function(orderItem) {
    return (
      orderItem.id.toString() === item.id.toString() &&
      orderItem.bundleItems.length === 0 &&
      orderItem.attachments.filter(function (a) {
        return hasPreviousAttachment(
          a, attachments, attachmentIndex, attachmentValueIndex
        )
      }).length === orderItem.attachments.length
    )
  })
}

function hasPreviousAttachment(
  attachment, attachments, attachmentIndex, attachmentValueIndex
) {
  var previousAttachments = attachments.slice(0, attachmentIndex)

  var attachmentToCompare = previousAttachments.find(function (a) {
    return a.name === attachment.name
  })

  if (!attachmentToCompare) {
    return false
  }

  var sameAttachmentValue = shallowEqual(
    attachment.content,
    attachmentToCompare.values[attachmentValueIndex]
  )

  return sameAttachmentValue
}

/* Helper functions */

function serializeRequests(requests) {
  return requests.reduce(function (acc, request) {
    if (!acc) {
      return request()
    }

    return acc.then(request)
  }, null)
}

function is(x, y) {
  if (x === y) {
    return x !== 0 || 1 / x === 1 / y;
  } else {
    return x !== x && y !== y;
  }
}

function shallowEqual(objA, objB) {
  if (is(objA, objB)) {
    return true
  }

  if (typeof objA !== 'object' || objA === null || typeof objB !== 'object' || objB === null) {
    return false
  }

  var keysA = Object.keys(objA)
  var keysB = Object.keys(objB)

  if (keysA.length !== keysB.length) {
    return false
  }

  // Test for A's keys different from B.
  for (var i = 0; i < keysA.length; i++) {
    if (!hasOwnProperty.call(objB, keysA[i]) || !is(objA[keysA[i]], objB[keysA[i]])) {
      return false
    }
  }

  return true
}


// Execute code
addItemWithAttachment(item, attachments)