feat(add-item): handling addItem method

src/index.js

@@ -5,6 +5,8 @@
  */
 
 import { _config } from '@ecomplus/utils'
+import addItem from './methods/add-item'
+import fixItem from './methods/fix-item'
 
 /**
  * Vanilla JS library to handle shopping cart object on E-Com Plus stores.
@@ -57,7 +59,13 @@ export default function (storeId, storageKey = _key, localStorage = _storage) {
    * @name EcomCart#data
    * @type {array<string>}
    */
-  this.data = {}
+  this.data = {
+    items: []
+  }
+
+  // instance methods
+  this.addItem = addItem
+  this.fixItem = fixItem
 
   if (localStorage && storageKey) {
     // try to preset cart data from storage

src/lib/fix-item-quantity.js

@@ -0,0 +1,12 @@
+export default item => {
+  // fix item quantity if needed
+  // use minimun quantity 1 by default
+  const min = item.min_quantity || 1
+  const max = item.max_quantity
+  if (typeof item.quantity !== 'number' || isNaN(item.quantity) || item.quantity < min) {
+    item.quantity = min
+  } else if (max && item.quantity > max) {
+    item.quantity = max
+  }
+  return item
+}

src/methods/add-item.js

@@ -0,0 +1,70 @@
+import { randomObjectId } from '@ecomplus/utils'
+import fixItemQuantity from './../lib/fix-item-quantity'
+
+// add item to cart
+export default ({ cart, saveCart }, newItem, save = true) => {
+  // check required fields
+  if (typeof newItem.product_id !== 'string' ||
+    typeof newItem.quantity !== 'number' || !(newItem.quantity >= 0) ||
+    typeof newItem.price !== 'number' || !(newItem.price >= 0)) {
+    // trying to add invalid item object
+    return null
+  }
+
+  let fixedItem
+  for (let i = 0; i < cart.items.length; i++) {
+    const item = cart.items[i]
+    // check IDs
+    if (item.product_id === newItem.product_id && item.variation_id === newItem.variation_id) {
+      // same product and variation
+      // update quantity and price
+      item.quantity += newItem.quantity
+      if (newItem.price) {
+        item.price = newItem.price
+      }
+      if (newItem.final_price) {
+        item.final_price = newItem.final_price
+      }
+      fixedItem = fixItemQuantity(item)
+    }
+  }
+
+  if (!fixedItem) {
+    if (!newItem._id) {
+      // generate random ObjectID
+      newItem._id = randomObjectId()
+    }
+    // add item to cart
+    cart.items.push(newItem)
+    fixedItem = fixItemQuantity(newItem)
+  }
+
+  if (save) {
+    saveCart()
+  }
+  return fixedItem
+}
+
+/**
+ * @method
+ * @name EcomCart#addItem
+ * @description Push new item to cart data and save.
+ *
+ * @param {item} newItem - New cart item object
+ * @param {boolean} [save=true] - Save cart data
+ *
+ * @returns {item|null} Returns the saved item object (with ID) or null
+ * when new item object is invalid.
+ *
+ * @example
+
+cart.addItem({
+  product_id: '123a5432109876543210cdef',
+  sku: 's-MP_2B4',
+  name: 'Mens Pique Polo Shirt',
+  quantity: 4,
+  price: 42.9,
+  keep_item_price: false
+})
+
+ */