For Each: forEach(function(singleItem) {
});
forEach() is used to run a function on every item in an array.

var priceList = [345, 566, 23, 45, 12];

var totalPrice = 0;
priceList.forEach(function(singlePrice) {
   console.log('Single price:', singlePrice);

   totalPrice = totalPrice + singlePrice
});


console.log(totalPrice); // 991

var items = [
    {
        "index": 1,
        "item_id": "41499884552324",
        "product_id": "7135045746820",
        "variant_id": "41499884552324",
        "item_name": "7 Shakra Bracelet",
        "quantity": 2,
        "price": 5400,
        "discount": 0,
        "item_category": "Bracelet",
        "item_brand": "Company 123",
        "item_variant": "Blue"
    },
    {
        "index": 2,
        "item_id": "41499881439364",
        "product_id": "7135044173956",
        "variant_id": "41499881439364",
        "item_name": "Black Leather Bag",
        "quantity": 1,
        "price": 3800,
        "discount": 0,
        "item_brand": "partners-demo"
    }
];

var totalQuantity = 0; 
items.forEach(function(singleItem) {
  totalQuantity = totalQuantity + singleItem.quantity;
});

console.log(totalQuantity); // total quantity