I have a code where i must add new key. The name is total. The properties total exist equal with quantity properties where the total is property quantity multiple with property price. In my code i use spread operator to get ...product and i want add key total and input to ...product. How i add key total ?

const axios = require("axios");

const url = "";
const getRequest = async (url) => {
  return (await axios.get(url)).data;
};
const result = async () => {
const carts = await getRequest("http://fakestoreapi.com/carts ");
const idProducts = await getRequest("http://fakestoreapi.com/products");


const merged = carts.map(cart => {
  return {
    ...cart,
    products: cart.products.map(product =>{
      return {
        ...product, 
//total : product.quantity * product.price,
        ...idProducts.find(item => product.productId === item.id)

      }
    })
  }
})
console.log(JSON.stringify(merged,null,2));
};
result();