How to update localstorage object value from index and key

Question

I need this solution for my project. its very important for me. i want to update object value with key and index, from local storage FOR my cart application.

(Decrease button for product quantity in cart)

Exmp.

function decreaseQuantity(index) {
  var oldQty = localStorage.cart[index].quantity;
  var newQty = oldQty - 1;
  localStorage.setItem(cart[index].quantity, newQty);
}

Answer 1

You can't store complex object in localStorage , you can store data as string only.

If you want to store the cart object to locaStorage , you need to serialize it as string using JSON.stringify and store it like following.

window.localStorage.setItem('cart', JSON.stringify(cart));

Note: here 'cart' is the key.

To get back, change it and store back, you need to do like following.

 var data = window.localStorage.getItem('cart');
        if (data != null) {
            let cart= JSON.parse(data);
              cart[index].quantity = cart[index].quantity -1;
             window.localStorage.setItem('cart', JSON.stringify(cart));

        } 

Answer 2

its worked for me @PSK thanks for your efforts @adiga I guess I made a logic error. thank you too, for your interest !